Bill Lewis received his M.D. from the University of Texas at San Antonio in 1976. He He spent nine years at the University of Minnesota, where he completed his residency, chief residency, and organ transplant fellowship. Lewis also held a surgery residency at Vanderbilt University School of Medicine in 1987.

From 1994 to 1996, Lewis served as director of Nashville's Centennial Medical Center's transplant program. He was also a clinical instructor at Vanderbilt University's Department of Surgery from 1988 until his death, clinical assistant at Meharry Medical College from 1993 to 1995, and assistant professor of surgery at Southern Illinois University School of Medicine from 1985 to 1987.