William H. Bullock, 70, a Washington physican who specialized in hematology and who was a retired professor at the Howard University medical school, died Sept. 18 at D.C. General Hospital after a heart attack.

He was stricken while driving his car on Pennsylvania Avenue SE shortly before midnight Sept. 17. D.C. police said the vehicle went out of control and struck a tree and that no other persons were involved in the accident. Dr. Bullock was pronounced dead on arrival at D.C. General.

A lifelong resident of Washington, he was a graduate of Dunbar High School. He received bachelor's and medical degrees at Howard in 1940 and 1944, respectively. In 1950 and 1951, he was a Rockefeller Fellow in hematology at the University of Michigan.

He established a medical practice in Washington in 1950, and continued it until his death. He taught at the Howard medical school until retiring in 1977.

He also had been a consultant in hematology at the Veterans Hospital, a staff physician and consultant in hematology at D.C. General Hospital and a staff physician and hematologist at the Freedmen's Hospital, which is now Howard University Hospital.

Dr. Bullock had served on the secretary of health, education and welfare's National Advisory Committee on Sickle Cell Disease. He was a diplomate of the American Board of Internal Medicine and a fellow of the American College of Physicians and the International Society of Hematology.

He was a director of the D.C. chapter of the American Red Cross and a member of the D.C. Medical Society, the Medico Chirurgical Society, the Blood Club, the International Society of Internal Medicine, the American Medical Association and the National Medical Association.

Survivors include a sister, Dr. Bennetta Bullock Washington, the wife of former D.C. mayor Walter E. Washington, of Washington; and two brothers, Dr. Samuel C. Bullock of Philadelphia and Joseph B. Bullock of Washington.