 After graduating from Columbia University College of Physicians and Surgeons in 1939 with Alpha Omega Alpha honor, Janowitz did a two-year fellowship in clinical pathology.In 1942 he joined the US Army as a medic in World War II and until 1946 served as such at its Medical Corps.While serving at an Arkansas-based Army hospital, Janowitz became acquainted with Thomas Urmy, a gastroenterologist from Boston.