Carl D. Corse, 78, a retired State Department official who was a specialist in international trade, died of cardiopulmonary arrest Jan. 26 at the South Seminole Medical Center in Longwood, Fla.

Mr. Corse, a resident of Winter Park, Fla., was chief of the trade agreement division of the State Department and chairman of international trade agreements from 1955 to 1958. He was principal negotiator for the U.S. delegation at three rounds of tariff negotiations under the General Agreement on Tariffs and Trade (GATT) between 1950 and his retirement in 1962.

As a Foreign Service officer he had served in the U.S. missions to the European Coal and Steel Community in Luxembourg and to the European Economic Community in Brussels in the late 1950s and in 1960.

At his retirement he held the rank of minister to the Council of GATT.

Mr. Corse was born in Verndale, Minn., and graduated from the University of Minnesota, where he also earned a master's degree in economics.

He joined the State Department in 1935 and moved to Florida upon his retirement.

His wife, Grace Webber Corse, died in 1971.

Survivors include a daughter, Nancy Corse Reed of Winter Park, Fla.; two sons, William C., of Dickerson, Md., and Carl D. Jr., of Annapolis; a sister, Vivian C. Burnstead of Minneapolis; seven grandchildren, and five great-grandchildren.