Exhibit 99.1

STERIS CORPORATION ANNOUNCES FISCAL 2014 FOURTH QUARTER

AND FULL YEAR RESULTS

• Strong fourth quarter results to end the year

• Full year reported EPS of $2.17; record full year adjusted EPS of $2.48

• Fiscal 2015 outlook calls for double-digit growth for revenue and EPS

Mentor, Ohio (May 8, 2014)—STERIS Corporation (NYSE: STE) today announced financial results for its fiscal 2014 fourth quarter and full year ended March 31, 2014. As reported, fiscal 2014 fourth quarter revenue was $465.3 million compared with $428.2 million in the fourth quarter of fiscal 2013. Operating income for the fourth quarter was $59.6 million compared with $65.1 million in the fourth quarter of fiscal 2013. Net income was $38.9 million, or $0.65 per diluted share, compared with net income of $41.4 million, or $0.70 per diluted share in the fourth quarter of fiscal 2013. The reported financial results for these periods reflect the $20.5 million restructuring charge in the fourth quarter of fiscal 2014, the SYSTEM 1 Rebate Program in fiscal 2013, as well as acquisition related expenses, amortization of intangibles and certain other items in both periods. Please refer to the attached schedules for additional information, including reconciliations of adjusted “non-GAAP financial measures” to reported results.

Adjusted Results

On an adjusted basis, fiscal 2014 fourth quarter revenue increased 9% to $465.3 million compared with adjusted revenue of $426.2 million in the fourth quarter of fiscal 2013, driven by double digit growth in Healthcare and high single digit growth in Isomedix. Adjusted operating income for the fourth quarter increased 32% to $86.5 million, compared with adjusted operating income for the fourth quarter of fiscal 2013 of $65.4 million. Adjusted net income for the fourth quarter of fiscal 2014 increased 30% to $54.2 million, or $0.91 per diluted share, compared with adjusted net income for the previous year of $41.5 million, or $0.70 per diluted share. The improvement in profit was driven by the increase in volume and operating expense leverage.

“We are pleased to report another record year,” said Walt Rosebrough, President and Chief Executive Officer of STERIS. “On an adjusted basis, we grew the top-line 10% and operating income 14% in fiscal 2014. We anticipate another record year of revenue and adjusted earnings for fiscal 2015, and are excited about the way our people are performing and the platforms we are building to realize our long-term objectives.”

STERIS Corporation

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Segment Results

As reported, Healthcare revenue in the quarter was $352.0 million compared with $317.4 million in the fourth quarter of fiscal 2013. On an adjusted basis, revenue increased 12% to $352.0 million compared with adjusted revenues of $315.4 million in the fourth quarter of fiscal 2013. Contributing to the quarter, service revenue increased 16%, capital equipment revenue grew 13%, and consumable revenue grew 5%.

As reported, Healthcare operating income was $37.6 million compared with $43.0 million in last year’s fourth quarter. Adjusted segment operating income increased substantially to $62.3 million in the fourth quarter of fiscal 2014 compared with $42.9 million in the fourth quarter of fiscal 2013. The increase in adjusted operating income year-over-year was primarily due to the increased volume, the benefit of acquisitions and operating expense leverage.

Life Sciences fourth quarter revenue declined 1% to $63.7 million compared with $64.3 million in the fourth quarter of fiscal 2013. Consumable revenue growth of 9% was more than offset by a 5% decline in capital equipment revenue and a 7% decrease in service revenue. As reported, Life Sciences operating income was $11.4 million compared with $12.3 million in the prior year fourth quarter. Adjusted segment operating income declined slightly to $12.0 million in the current quarter on the lower volume, compared with $12.3 million in the fourth quarter of fiscal 2013.

Fiscal 2014 fourth quarter revenue for Isomedix Services was $49.4 million compared with $45.8 million in the same period last year, an increase of 8%. Revenue benefited from capacity expansions and increased volume from the Company’s core medical device Customers. As reported, operating income was $12.7 million in the quarter compared with $12.1 million in the fourth quarter of last year. Adjusted segment operating income increased 14% to $14.2 million in the fourth quarter of fiscal 2014 compared with $12.4 million in the fourth quarter of fiscal 2013, driven primarily by the increased volume.

Full Year Results

As reported, fiscal 2014 full year revenue increased 8% to $1.62 billion compared with $1.50 billion in fiscal 2013. On an adjusted basis, revenue increased 10% in fiscal 2014. As reported, fiscal 2014 operating income was $206.8 million compared with $242.8 million in fiscal 2013. Adjusted operating income increased 14% to $250.1 million in fiscal 2014 compared with $219.7 million in fiscal 2013.

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As reported, fiscal 2014 net income was $129.4 million or $2.17 per diluted share, compared with net income of $160.0 million or $2.72 per diluted share in fiscal 2013. Adjusted net income for fiscal 2014 increased 7% to $147.9 million or $2.48 per diluted share compared with $137.8 million or $2.34 per diluted share in fiscal 2013.

Cash Flow

Net cash provided by operations for fiscal 2014 was $209.6 million, compared with $227.8 million in fiscal 2013. Free cash flow (see note 1) for fiscal 2014 was $128.0 million compared with $140.4 million in the prior year. The decline in free cash flow is primarily due to payments for the Company’s annual incentive compensation program which did not occur in fiscal 2013, as well as the impact of strong working capital improvements in the prior year.

Dividend Announcement

The Company announced today that STERIS’s Board of Directors has authorized a quarterly dividend of $0.21 per common share. The dividend is payable June 26, 2014 to shareholders of record at the close of business on June 5, 2014.

Outlook

Based upon current trends, the Company expects revenue growth in the range of 15-17% in fiscal 2015 when compared with fiscal 2014. Adjusted earnings per diluted share are anticipated to be in the range of $2.78 to $2.91 for the full fiscal year. This outlook reflects certain key assumptions, some of which are listed below:

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Fiscal 2015 free cash flow (see note 1) is anticipated to be approximately $135 million. Capital expenditures are anticipated to be approximately $95 million, reflecting the impact of acquisitions, continued expansion within Isomedix, new product development and general maintenance and repair for existing facilities.

Conference Call

In conjunction with this release, STERIS Corporation management will host a conference call today at 10:00 a.m. Eastern time. The conference call can be heard live over the Internet at www.steris-ir.com or via phone by dialing 1-800-369-8428 in the United States and Canada, and 1-773-799-3378 internationally, then referencing the password “STERIS”.

For those unable to listen to the conference call live, a replay will be available beginning at 12:00 p.m. Eastern time today, May 8, 2014, either over the Internet at www.steris-ir.com or via phone by calling 1-866-501-2958 in the United States and Canada, and 1-203-369-1826 internationally.

Annual Meeting of Shareholders

The Company will hold its annual meeting of shareholders on July 30, 2014. Further information regarding the time and location will be provided in the Company’s annual report and proxy materials.

About STERIS

The mission of STERIS Corporation is to help our Customers create a healthier and safer world by providing innovative healthcare and life science product and service solutions around the globe. The Company is listed on the New York Stock Exchange under the symbol STE. For more information, visit www.steris.com.

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(1) Free cash flow is a non-GAAP number used by the Company as a measure to gauge its ability to fund future debt principal repayments, growth outside of core operations, repurchase common shares, and pay cash dividends. Free cash flow is defined as cash flows from operating activities less purchases of property, plant, equipment and intangibles, net, plus proceeds from the sale of property, plant, equipment and intangibles. STERIS’s calculation of free cash flow may vary from other companies.

This press release and the referenced conference call may contain statements concerning certain trends, expectations, forecasts, estimates, or other forward-looking information affecting or relating to the Company or its industry, products or activities that are intended to qualify for the protections afforded “forward-looking statements” under the Private Securities Litigation Reform Act of 1995 and other laws and regulations. Forward-looking statements speak only as to the date of this press release and the referenced conference call, and may be identified by the use of forward-looking terms such as “may,” “will,” “expects,” “believes,” “anticipates,” “plans,” “estimates,” “projects,” “targets,” “forecasts,” “outlook,” “impact,” “potential,” “confidence,” “improve,” “optimistic,” “deliver,” “comfortable,” “trend”, and “seeks,” or the negative of such terms or other variations on such terms or comparable terminology. Many important factors could cause actual results to differ materially from those in the forward-looking statements including, without limitation, disruption of production or supplies, changes in market conditions, political events, pending or future claims or litigation, competitive factors, technology advances, actions of regulatory agencies, and changes in laws, government regulations, labeling or product approvals or the application or interpretation thereof. Other risk factors are described herein and in the Company’s Form 10-K and other securities filings. Many of these important factors are outside STERIS’s control. No assurances can be provided as to any result or the timing of any outcome regarding matters described in this press release, the referenced conference call or otherwise with respect to any regulatory action, administrative proceedings, government investigations, litigation, warning letters, consent decree, rebate program, transition, cost reductions, business strategies, earnings or revenue trends or future financial results. References to products, the consent decree, the transition or rebate program, or the class action settlement, are summaries only and should not be considered the specific terms of the decree, settlement, program or product clearance or literature. Unless legally required, the Company does not undertake to update or revise any forward-looking statements even if events make clear that any projected results, express or implied, will not be realized. Other potential risks and uncertainties that could cause actual results to differ materially from those in the forward-looking statements include, without limitation, (a) the potential for increased pressure on pricing or costs that leads to erosion of profit margins, (b) the possibility that market demand will not develop for new technologies, products or applications or business initiatives will take longer, cost more or produce lower benefits than anticipated, (c) the possibility that application of or compliance with laws, court rulings, certifications, regulations, regulatory actions, including without limitation those relating to FDA warning notices or letters, government investigations, the outcome of any pending FDA requests, inspections or submissions, or other requirements or standards may delay, limit or prevent new product introductions, affect the production and marketing of existing products or services or otherwise affect Company performance, results, prospects or value, (d) the potential of international unrest, economic downturn or effects of currencies, tax assessments, adjustments, or anticipated rates, raw material costs or availability, benefit or retirement plan costs, or other regulatory compliance costs, (e) the possibility of reduced demand, or reductions in the rate of growth in demand, for the Company’s products and services, (f) the possibility that anticipated growth, cost savings, new product acceptance, performance or approvals, or other results may not be achieved, or that transition, labor, competition, timing, execution, regulatory, governmental, or other issues or risks associated with our business, industry or initiatives including, without limitation, the consent decree, the transition from the SYSTEM 1 processing system and adjustments to related reserves, or those matters described in our Form 10-K for the year ended March 31, 2013 and other securities filings, may adversely impact Company performance, results, prospects or value, (g) the possibility that anticipated financial results or benefits of recent acquisitions or of our restructuring efforts will not be realized or will be other than anticipated, (h) the effects of contractions in credit availability, as well as the ability of our Customers and suppliers to adequately access the credit markets when needed, and (i) those risks described in our securities filings including our Annual Report on Form 10-K for the year ended March 31, 2013, and other securities filings.

Contact: Julie Winter, Director, Investor Relations at 440-392-7245.

STERIS Corporation

Consolidated Condensed Statements of Operations

(In thousands, except per share data)

STERIS Corporation

Consolidated Condensed Balance Sheets

(In thousands)

STERIS Corporation

Segment Data

(In thousands)

STERIS Corporation

Consolidated Condensed Statements of Cash Flows

(In thousands)

The following table presents a financial measure which is considered to be “non-GAAP financial measures” under Securities Exchange Commission rules. Free cash flow is defined by the Company as cash flows from operating activities less purchases of property, plant, equipment and intangibles, net (capital expenditures) plus proceeds from the sale of property, plant, equipment and intangibles. The Company uses free cash flow as a measure to gauge its ability to fund future principal debt repayments and growth outside of core operations, repurchase common shares, and pay cash dividends. STERIS’s calculation of free cash flow may vary from other companies.

STERIS Corporation

Non-GAAP Earnings Per Share and Outlook

Non-GAAP financial measures are presented with the intent of providing greater transparency to supplemental financial information used by management and the Board of Directors in their financial analysis and operational decision making. These amounts are disclosed so that the reader has the same financial data that management uses with the belief that it will assist investors and other readers in making comparisons to our historical operating results and analyzing the underlying performance of our operations for the periods presented.

We believe that the presentation of these non-GAAP financial measures, when considered along with our GAAP financial measures and the reconciliation to the corresponding GAAP financial measures, provide the reader with a more complete understanding of the factors and trends affecting our business than could be obtained absent this disclosure. It is important for the reader to note that the non-GAAP financial measure used may be calculated differently from, and therefore may not be comparable to, a similarly titled measure used by other companies.

STERIS Corporation

Non-GAAP Financial Measures

(In thousands, except per share data)

Non-GAAP financial measures are presented with the intent of providing greater transparency to supplemental financial information used by management and the Board of Directors in their financial analysis and operational decision making. These amounts are disclosed so that the reader has the same financial data that management uses with the belief that it will assist investors and other readers in making comparisons to our historical operating results and analyzing the underlying performance of our operations for the periods presented.

We believe that the presentation of these non-GAAP financial measures, when considered along with our GAAP financial measures and the reconciliation to the corresponding GAAP financial measures, provide the reader with a more complete understanding of the factors and trends affecting our business than could be obtained absent this disclosure. It is important for the reader to note that the non-GAAP financial measure used may be calculated differently from, and therefore may not be comparable to, a similarly titled measure used by other companies.

STERIS Corporation

Unaudited Supplemental Financial Data

Forth Quarter Fiscal 2014

As of March 31, 2014

We believe that the presentation of these non-GAAP financial measures, when considered along with our GAAP financial measures and the reconciliation to the corresponding GAAP financial measures, provide the reader with a more complete understanding of the factors and trends affecting our business than could be obtained absent this disclosure. It is important for the reader to note that the non-GAAP financial measure used may be calculated differently from, and therefore may not be comparable to, a similarly titled measure used by other companies.

This supplemental data is consistent with publicly disclosed information provided in quarterly conference calls, earnings releases and SEC filings, and is subject to all definitions, precautions and limitations contained in those disclosures. Please see the Company’s most recent 10-K for definitions (and reconciliation where appropriate) of adjusted measures, backlog, free cash flow and net debt.