Jan Adriaan Laan, 73, a consultant in oilseed technology and a resident of the Washington area since 1954, died Thursday at Suburban Hospital in Bethesda. He had a heart ailment.

Mr. Laan was born in Wormerveer, The Netherlands. He graduated from the University of Amsterdam and did graduate work in economics before joining Olie-Industrie N.V., a family business that owned oilseed and rice mills in The Netherlands. The company now is part of Unilever, a major food distributor.

During World War II, Mr. Laan was an officer in the Rijdende Artillerie, a horse-artillery unit in the Dutch army. During the German occupation, he was a member of the underground.

Mr. Laan moved to the United States in 1954 and settled in Bethesda. He was a consultant in oilseed technology, which concerns extracting oil from soybeans and other plants, until his death.

He was a member of the American Oil Chemists Society and the Garden Club of Montgomery County. He specialized in growing roses.

Mr. Laan, who maintained a residence in St. Maarten, The Netherlands Antilles, for many years, is survived by his wife, Leonore, whom he married in 1954, of Bethesda; two sons, Remmert, of Minneapolis, and Willem, of Washington, and one sister, Eva Mouthaan-Laan of The Netherlands.