Jack Frankel, 68, a dairy farmer and state legislator in Connecticut who became an official of the Peace Corps and the World Bank, died at Suburban Hospital May 29 after a heart attack.

Mr. Frankel, who lived in the Somerset section of Chevy Chase, was born in New York City. He grew up there and in Lebanon, Conn., where for 30 years he ran a dairy farm. He also served two terms as a Democrat in the Connecticut legislature.

In 1962, he joined the Peace Corps; for the next five years he was deputy director of its mission in Iran. In 1967, he was assigned to the agency's headquarters in Washington, where he spent the next five years as an agricultural program officer.

From 1972 to 1975, Mr. Frankel was a private consultant in Tanzania and Brazil on agricultural and other economic development matters. He then returned here and joined the World Bank, where he was a senior agriculturalist until he retired in 1981.

Mr. Frankel was a member of the Somerset Town Council in Chevy Chase.

Survivors include his wife, Judith, of Chevy Chase; two children, David of Bozeman, Mont., and Sara of Kingston, Jamaica; a brother, Eugene, of Norwich, Conn., and a sister, Judith Lauter of San Diego.