Bowen began his career as an intern at Memorial Hospital in South Bend, Indiana, in 1942. From 1943 to 1946 he served in the Medical Corps of the United States Army, rising from the rank of 1st lieutenant to captain. On his return from World War II, he set up his own medical practice in his home town of Bremen, Indiana, which he discontinued in 1972. As a physician he was instrumental in helping establish a community hospital for Bremen in 1956. During this time, he also was a member of staff for various hospitals in Indiana and served as coroner for Marshall County, Indiana. In 1981 he took up the post of clinical professor of family medicine at Indiana University.