Commerce Bank Has Discovered an Attempted Hacking on Its Computer Systems

For Immediate Release For more information, please contact: Sharon Bock, Regional Marketing Manager, 816-234-2632 [email protected] or Paula Oakman, Regional Marketing Representative, 816-234-2308 or [email protected]

A statement from Commerce Bank

Lawrence, KS, October 9, 2007 –Commerce Bank has discovered an attempted hacking on a computer system. The hacking was detected and quickly shut down. Commerce immediately notified law enforcement authorities and is working with them in their investigation.

Commerce has determined that a total of 20 customers had personal data compromised in one database of 3,000 records on that computer system, or one quarter of one percent of our customers. Commerce has notified the initial 20 customers as well as the remaining 3,000 customers in that database regarding a possibility that their information has been accessed. In addition, Commerce is providing free credit monitoring service to affected customers for 24 months, plus a toll-free number to call with any questions or concerns.

At Commerce Bank, we take the security of our customers' accounts very seriously. We are carefully and actively monitoring all accounts for fraudulent activity and we employ sophisticated fraud detection software to review account transactions. We advise all our customers to regularly and carefully monitor their accounts and to contact us immediately if they see any fraudulent charges. -more- Add Two Commerce Bank Statement

About Commerce Bank Commerce Bank, N.A. is a subsidiary of Commerce Bancshares, Inc. (NASDAQ: CBSH), a $15.5 billion regional bank holding company. For more than 140 years, Commerce Bancshares has been meeting the financial services needs of individuals and businesses. Commerce Bancshares provides a diversified line of financial services, including business and personal banking, wealth management and estate planning and investments through its subsidiary and affiliated companies. Commerce Bancshares’ banking companies currently operate in approximately 360 locations in Missouri, Kansas, Illinois, Oklahoma and Colorado. Commerce Bancshares also has operating subsidiaries involved in mortgage banking, leasing, credit-related insurance, venture capital and real estate activities.

For additional information, please visit www.commercebank.com or email [email protected].