George Radin, 85, founder and president of the International Development Foundation and an attorney who had specialized in international law here since 1941, died Sunday at the Colonial Villa Nursing Home in Washington following a stroke.

Mr. Radin, who was born in Serbia, came to this country in 1911. He earned undergraduate and law degrees from Columbia University. He then practiced law in New York City and also had offices in Belgrade, Yugolavia, and Zurich, Switzerland. During those years, Mr. Radin established the Serbian health cooperative movement in Yugoslavia.

During World War II, he moved to Washington, where he was a special representative of King Peter of Yugoslavia. He also was an official of the Lend-Lease agency, the major program under which the United States furnished assistance to the allies.

In 1946, he set up a private law practice in Washington that had associates in New York and Zurich. He was an advisor to the government on economic aid programs.

In addition to founding the IDF, a privately-funded organization that assists developing countries through self-help projects, he set up the Serbian Research Foundation at American University to study the history and culture of the Yugoslav people.

With the historian Charles Beard, Mr. Radin was the author of "The Balkan Pivot: Yugoslavia." He also wrote "Postwar Economic Reconstruction: A Practical Plan for the Balkans," which was published by the Carnegie Endowment for International Peace.

Mr. Radin was active in the Christian Serbian Orthodox Church.

He was a member of the D.C. and New York City bar associations and the American Society of International Lawyers.

He was a member of the Metropolitan Club and the Congressional Country Club. Mr. Radin was a resident of the old Wardman Park Hotel in Washington for over 30 years. He moved to the Colonial Villa Nursing Home in 1976.

Survivors include his wife, Katarina Hadji-Popovitch Radin, a daughter, Mrs. Harry R. Stringer Jr., and one grandchild, all of Washington.