Exhibit 99.1

FOR IMMEDIATE RELEASE

July 22, 2009

CULLEN/FROST REPORTS SECOND QUARTER RESULTS

SAN ANTONIO – Cullen/Frost Bankers, Inc. (NYSE: CFR) today reported net income for the second quarter of 2009 of $37.9 million, or $.63 per diluted common share, compared to second quarter 2008 earnings of $52.5 million, or $.89 per diluted share, despite solid increases over the same time period in taxable equivalent net interest income, loans and record deposit growth. An industry-wide FDIC special assessment impacted the company’s earnings by $7.3 million, or $.08 per share on an after-tax basis.

The provision for possible loan losses increased to $16.6 million from $6.3 million for the same quarter a year ago, while the allowance for possible loan losses as a percentage of loans increased to 1.42 percent from 1.13 percent at last year’s second quarter.

Returns on average assets and equity were .98 percent and 8.35 percent, respectively, compared to 1.56 percent and 13.44 percent for the same period a year earlier.

For the second quarter of 2009, net interest income on a taxable-equivalent basis rose 5.9 percent to $144.3 million, compared to the $136.2 million reported for the same quarter of 2008. Average loans were $8.8 billion, up 7.3 percent from the $8.2 billion reported for the second quarter of 2008, but were

flat compared to the previous quarter as businesses respond to the current economic conditions. Average deposits for the quarter increased 17.0 percent to $12.2 billion from the $10.4 billion reported a year earlier. Average deposits grew a record $725 million from the prior quarter, as the company has seen deposits increase steadily as customers continue to build cash reserves during these uncertain times, while also seeking the safety and soundness of Frost.

“We continue to operate well in a difficult banking environment and are making sound decisions to position our company to succeed when the national and global economies improve,” said Cullen/Frost CEO Dick Evans. “Our strong capital levels continue to give me confidence, and in light of the current economy, the increase in provision for loan losses was prudent. Credit quality, although challenging, remains at manageable levels.

“Given the uncertainty customers are feeling about the broader economy, we are helping them navigate through the current environment. As they regain their confidence, they will begin to reinvest,” said Evans. “Texas remains well positioned for growth, which is very positive for us.

“We continue to open new financial centers to serve our customers, with four locations opening this year, including our first in Plano in the Dallas region, and additional centers in Austin, San Antonio and Houston. There is still good growth opportunity in the Texas markets we serve, and we continue to bring in new relationships as customers understand the benefit of our value proposition.

“Just last month, we received the Morningstar ratings on Frost Investment Advisors mutual fund family, and I am pleased to say that six Frost funds received the Five-Star Overall Morningstar Rating. This validates our fund management expertise in providing outstanding service and investment insight to both institutional and retail investors.

“As always, I thank our outstanding employees, whose determination, enthusiasm and commitment to our company and its values help us take good care of customers,” Evans continued.

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For the first six months of 2009, net income was $82.8 million, or $1.39 per diluted common share, compared to $105.3 million, or $1.78 per diluted common share, for the first six months of 2008. Returns on average assets and average equity for the first six months of 2009 were 1.10 percent and 9.32 percent, respectively, compared to 1.57 percent and 13.66 percent for the same period in 2008.

Other noted financial data for the second quarter follows:

Trust fees were $16.9 million, down $2.1 million or 11.4 percent, compared to $19.0 million in the second quarter of 2008. Most of this decrease relates to lower oil and gas trust management fees and lower investment fees. Investment fees which represent approximately 70 percent of total trust fees and are generally assessed based on the market value of trust assets. Trust assets were $21.7 billion at the end of the second quarter, compared to $23.9 billion for the second quarter a year ago. This market value includes both assets that are managed and those held in custody.

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Service charges on deposits were $25.2 million, up 16.3 percent, or $3.5 million, compared to the same quarter the previous year. Impacting this increase was a $3.0 million increase in service charges on commercial accounts, resulting from higher treasury management fees. A drop in the earnings credit rate for commercial accounts, compared to a year earlier, affected treasury management fees. When interest rates are lower, customers earn less credit for their deposit balances, and this, in turn, increases the amount of service charges to be paid for through fees.

Other service charges and fees were $6.3 million, compared to $9.5 million reported in the same quarter a year earlier. During the second quarter of 2008, the company recognized $1.4 million in investment banking fees related to corporate advisory services. Also contributing to the decline were decreases in commission income for the sale of money market accounts, annuities and mutual funds.

Other income was $12.5 million, compared to $13.5 million for the same quarter a year earlier. This decrease was primarily the result of fewer gains on the sale of student loans, down $1.0 million from the second quarter last year.

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Cullen/Frost Bankers, Inc. will host a conference call on Wednesday, July 22, 2009, at 10:00 a.m. Central Time (CT) to discuss the results for the quarter. The media and other interested parties are invited to access the call in a “listen only” mode at 1-800-944-6430. Digital playback of the conference call will be available after 2:00 p.m. CT until midnight Sunday, July 26, 2009 at 1-800-642-1687 or 1-706-645-9291 for international calls, with Conference ID # of 19676201. The call will also be available by webcast at the URL listed below and available for playback after 2:00 p.m. CT. After entering the Web site, www.frostbank.com, go to “About Frost” on the top navigation bar, then click on Investor Relations.

Cullen/Frost Bankers, Inc. (NYSE: CFR) is a financial holding company, headquartered in San Antonio, with assets of $15.8 billion at June 30, 2009. The corporation provides a full range of commercial and consumer banking products, investment and brokerage services, insurance products and investment banking services. Frost operates more than 100 financial centers across Texas in the Austin, Corpus Christi, Dallas, Fort Worth, Houston, Rio Grande Valley and San Antonio regions. Founded in 1868, Frost is the largest Texas-based banking organization that operates only in Texas, with a legacy of helping clients with their financial needs during three centuries.

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Forward-Looking Statements and Factors that Could Affect Future Results

Certain statements contained in this Earnings Release that are not statements of historical fact constitute forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 (the “Act”), notwithstanding that such statements are not specifically identified as such. In addition, certain statements may be contained in the Corporation’s future filings with the SEC, in press releases, and in oral and written statements made by or with the approval of the Corporation that are not statements of historical fact and constitute forward-looking statements within the meaning of the Act. Examples of forward-looking statements include, but are not limited to: (i) projections of revenues, expenses, income or loss, earnings or loss per share, the payment or nonpayment of dividends, capital structure and other financial items; (ii) statements of plans, objectives and expectations of Cullen/Frost or its management or Board of Directors, including those relating to products or services; (iii) statements of future economic performance; and (iv) statements of assumptions underlying such statements. Words such as “believes”, “anticipates”, “expects”, “intends”, “targeted”, “continue”, “remain”, “will”, “should”, “may” and other similar expressions are intended to identify forward-looking statements but are not the exclusive means of identifying such statements.

Forward-looking statements involve risks and uncertainties that may cause actual results to differ materially from those in such statements. Factors that could cause actual results to differ from those discussed in the forward-looking statements include, but are not limited to:

Forward-looking statements speak only as of the date on which such statements are made. The Corporation undertakes no obligation to update any forward-looking statement to reflect events or circumstances after the date on which such statement is made, or to reflect the occurrence of unanticipated events.

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Cullen/Frost Bankers, Inc.

CONSOLIDATED FINANCIAL SUMMARY (UNAUDITED)

(In thousands, except per share amounts)

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Cullen/Frost Bankers, Inc.

CONSOLIDATED FINANCIAL SUMMARY (UNAUDITED)

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Cullen/Frost Bankers, Inc.

CONSOLIDATED FINANCIAL SUMMARY (UNAUDITED)

(In thousands, except per share amounts)

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Cullen/Frost Bankers, Inc.

CONSOLIDATED FINANCIAL SUMMARY (UNAUDITED)

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