Dr. William D. Tigertt, a retired brigadier general in the Army Medical Corps and a professor at the University of Maryland Medical School, where he was director of the clinical laboratories, died Sunday at Walter Reed Army Medical Center in Washington after a heart attack a week earlier.

Dr. Tigertt was 76 and lived in the 2 Charles Center Apartments.

Services for Dr. Tigertt were being held today at Old St. Paul's Episcopal Church, Charles and Saratoga streets.

He joined the Maryland faculty as professor of medicine, professor of pathology and associate chairman of the department of pathology in 1972 after he retired from the Army. He also helped to start a school for laboratory technicians at Maryland.

In the Army, he became an expert on preventive medicine and the causes and transmission of infectious diseases.

Dr. Tigertt is survived by his wife of 53 years, the former Helen Braack; a daughter, Susan T. Brookman of Baltimore; a son, William David Tigertt Jr. of Pleasant Ridge, Mich.; a brother, Carl Tigertt, and a sister, Dorothy Blackwood, both of Lancaster, Texas; and three grandchildren.