Alexander Leggin, 64, founder and president of Leggin & Associates Inc., an industrial consulting firm established in 1953, died of a heart attack Thursday at his home in Bethesda.

Mr. Leggin, who was trained as a chemist, also was president of World Searches Inc., a firm he founded that carries out trademark searches by computer.

A native of Hazelton, Pa., he grew up in Pittsburgh. He graduated from the University of Pittsburgh, where he was cadet colonel in the ROTC program, and later had a fellowship in chemistry at the Mellon Institute. He then headed a research division for the Pittsburgh Plate Glass Co.

During World War Ii, he was the chief chemical officer on the staff of Gen. Omar N. Bradley at the headquarters of the 12th Army Group in Europe. He received the Bronze Star and decorations from Belgium, France and Czechoslovakia. After the war, he founded the 12th Army Group Association.

Mr. Leggin moved to Washington in 1945 and headed the news service of the American Chemical Society.He was an assistant to the president of the Wyandotte Chemical Corp. before founding his own firm.

He was a member of the American Chemical Society, the American Institute of Chemists, the Washington Society of Investment Analysts and the Congressional Country Club.

Survivors include his wife, Gloria, and two children, Richard and Dorothy, all of the home; a brother, Edward, of Pittsburgh, and a sister, Mrs. Alex Solanik, of San Antonio, Tex.