Willis W. Alexander, 66, the executive vice president of the American Bankers Association until he retired last April with 16 years of service, died of cancer Oct. 27 at Commonwealth Hospital in Fairfax.

In 1969, Mr. Alexander joined the Washington office of the bankers association, a trade organization whose members represent 95 percent of the commercial banking industry in the country. In 1971 he supervised the move of its principal offices from New York to Washington.

In the course of his career here Mr. Alexander was credited with helping the ABA reach a consensus on legislation to deregulate interest rates and to end the differential on interest rates for savings and loan associations and commercial banks. Other issues on which he worked on Capitol Hill involved new forms of financial services and competition from nonbank institutions.

Mr. Alexander, who lived in Reston, was born in Trenton, Mo. He graduated from the University of Missouri and received a master's degree in business administration from the University of Pennsylvania. During World War II he served in the Navy in the Pacific and attained the rank of lieutenant commander.

After the war he went to work at the Trenton Trust Co., where he became president and chairman. He also was copublisher of his home-town newspaper, The Trenton Republican-Times, and taught economics at Trenton Junior College.

He moved to the Washington area as the chief staff official of the ABA after serving a one-year term as the organization's president. He had been president of the Missouri Bankers Association in 1959-1960.

His marriage to Doris Alexander ended in divorce.

Survivors include his wife, Sandy, and their two children, Meg and Mary Kay, all of Reston; three children by his first marriage, Eric Alexander of Bend, Ore., Barbara Babb of Chesterfield, Mo., and Tricia Elliot of Alexandria; a brother, Maurice Alexander of Jefferson City, Mo.; a sister, Martha Brewer of Dallas, and six grandchildren.