Dr. Richard B. Castell, 70, a retired family physician and director of Student Health Services at George Washington University, died of a heart ailment Saturday in a hospital in Kilmarnock, Va.

Dr. Castell maintained a private practice in the Mayflower Hotel from 1937 to 1961, and also was the hotel's physician for many years. He was the medical director of Equitable Life Insurance in Washington from 1961 uintil retiring in 1972.

He was a clinical instructor at George Washington University's medical school for many years and was university physician and director of Student Health Services at the University from 1956 to 1972.

He was a member of the American Medical Association, the Medical Society of the District of Columbia, the Virginia State Medical Society, the Royal Society of Medicine, the Washington Heart Association, and the George Washington University Medical Society.

Dr. Castell was a native of Washington and a graduate of Central High School. He graduated from George Washington University's medical school in 1935 and served both his internship and residency at George Washington University Hospital. He lived in Washington until retiring to Montross, Va., in 1972.

He served as a Navy doctor during World War II in both Europe and the Pacific, attaining the rank of lieutenant commander.

Survivors include his wife, Esther B., of Montross; a son, Richard C., of Silver Spring; two daughters, Linda Finan of Mount Holly, Va., and Nancy A. Castell of Washington.