STAMFORD, Conn., Jan. 26 -- Dr. Samuel P. Hardy, a widely known figure in the tennis world and captain of this country's Davis cup teams in 1920 and 1931, died here yesterday of a heart ailment in the Roger Smith Hotel. He was 76 years old, and had resided at the hotel for several months.

Dr. Hardy, who gave up a career as a physician to devote his life to tennis, had won championships in twelve countries. Last July he received an annual award from the Professional Lawn Tennis Association. He never had competed as a professional.

Born in Oakland, Calif., Dr. Hardy learned to play tennis at the age of 10 on his family's court. He won the Pacific Coast singles championship in 1894, '95, '96 and '98. With his brother, the late Dr. Sumner Hardy, also a physician he won the doubles championship there in 1892, '93, '95, '97 and '98.

Dr. Hardy was graduated from Stanford University in 1902. He received a medical degree from the University of California and practiced medicine in California and Nevada until 1908. In 1909 he moved to England and was a real estate broker from 1910 to 1915. In 1911, with J. C. Parke, he reached the finals of the Wimbledon doubles tournament.

Returning to California during World War I, Dr. Hardy became head of tennis promotion for A. G. Spalding and Bros. in New York in 1917. He retired from that firm a year ago because of poor health.

Dr. Hardy was United States clay court singles champion in 1917, and with C. S. Garland won the Western doubles tournament of 1917 and the United States clay court doubles of 1917 and 1918. In 1920 he won the doubles again with William Johnston.

As captain of the Davis Cup team of 1920, Dr. Hardy had been expected to play, but withdrew voluntarily after recognizing the ability of William T. Tilden and William M. Johnston, who defeated Austrailia at Auckland, New Zealand.

Dr. Hardy was active in the United States Davis Cup Committee and the Rules and Ranking Committees of the United States Lawn Tennis Association. He was a member of the All-England, Queen's and International Lawn Tennis Clubs of Great Britain, the International Lawn Tennis Club of the United States and the West Side Tennis Club of Forest Hills, Queens.

He is survived by his widow, Mrs. Sylvia Fowler Harris.