Edgar Underwood was commissioned through the Reserve Officer Training Corps program in 1936 upon graduation from the University of Alabama School of Medicine. He received a doctor of medicine degree from Tulane in June 1940. After serving as a Medical Officer in the Army Air Forces in World War II, he transferred to the U.S. Air Force when it became a separate branch of service in 1947. He retired in 1971 as a U.S. Air Force Brigadier General.