Sidney K. Lafoon, 73, a Foreign Service officer with the Department of State and a former U.S. consul general in Bermuda, died Wednesday at his home in Key Largo, Fla., following an apparent heart attack.

Mr. Lafoon retired from the Foreign Service in 1960, after 33 years of diplomatic service.He had served in Bogota, Baghdad, Iraq, and in China during the 1930s. Mr. Lafoon was the State Department representative on the Swedish liner, Gripsholm, during its historic voyages bringing American citizens to the United States during World War II.

After the war, Mr. Lafoon served four years in Uruguay and four years in Hungary before becoming consul general in Bermuda. He lived in Washington following his retirement and moved to Key Largo about a year ago. Mr. Lafoon was a native of Danieltown, Va.

He had been a member of the Metropolitan Club, the Chevy Chase Club and DACOR.

Survivors include his wife, Margaret J., of the home; two daughters, Sydney L. Mazario, of Napa, Calif., and Louise L. Greene, of Fitzwilliam, N.H. and a sister, Ruth L. Brown, of Richmond.

The family suggests that expressions of sympathy be in the form of contributions to the Ocean Reef Chapel Fund, Key Largo, Fla.