Joseph Leland Johnson, 96, a former dean of the Howard University medical school and chairman of its department of physiology, died of cancer Dec. 19 at his home at the Charter House retirement residence in Silver Spring.

Dr. Johnson joined the faculty of the Howard medical school in 1931 as chairman of the department of physiology. He was named dean of the medical school in 1946, and he held that post until 1955. He continued to teach physiology until 1971, when he retired.

Dr. Johnson, who lived in Washington until moving to Charter House last year, was born in Philadelphia. He served in the Army in World War I. He graduated from what is now Pennsylvania State University, and he received his medical degree from the University of Chicago. He also received a doctorate in physiology from the University of Chicago.

He was a member of the board of directors of the National Medical Association and a member of the Medico Chirurgical Society of the District of Columbia, the NAACP, Alpha Omega Alpha, which is an honorary medical society, and the Alpha Phi Alpha fraternity.

His first wife, the former Estellena Gardner, died in 1978. His second wife, Millie Harris, also died. His third wife, Dr. E. Mae McCarroll died earlier this year. He leaves no immediate survivors.