William M. Dunn, 68, a founder and retired official of the Communications Workers of America, died of cancer Friday at the Greater Baltimore Medical Center.

He had retired as executive assistant to the secretary treasurer of CWA in August, 1973. Since then he had divided his time between homes in Hyattsville and Fort Myers, Fla.

Born in Covington, Ky., Mr. Dunn was a graduate of Salmon P. Chase Law School in Cincinnati, where he worked in the plant engineering department of the Bell System operating company.

He helped found the Cincinnati Federation of Telephone Workers in the 1930s, and in 1938, became one of the founders of the CWA, which took in the telephone workers.

Mr. Dunn came to Washington in 1948, as the first assistant to the late Joseph A. Beirne, then CWA president. His particular interests were in politics and legislation.

In the late 1950s, the Canadian CWA delegates elected Mr. Dunn as their district director and he served in that capacity in Toronto until 1965. During that period he also was a member of the CWA executive board.

He then returned to Washington, to join the staff of the secretary-treasurer. In 1970, he was named executive assistant to then secretary-treasurer Glen E. Watts, who is now CWA president.

Afer retiring from CWA, Mr. Dunn became an active member of the National Council on Alcoholism. He also was labor adviser to the United Way of Metropolitan Washington.

He is survived by his wife, Laura Burroughs Dunn, of the homes; a daughter, Patricia Wiles, of Hawaii, and two grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to the American Cancer Society or the National Council on Alcoholism.