Dr. Leonard was born and raised in Spokane, Washington.  He attended University of Washington from 1964 - 1967 for his undergraduate training and University of Washington Medical School from 1967 - 1971.  He did his cardiovascular surgery training at the University of Minnesota from 1971 to 1980. 

While at the University of Minnesota he worked with Drs. Lillehei, Varco, and Castaneda who were the first surgeons to correct many of the initial open heart diseases in children.  He consolidated the practice of congenital heart surgery in Spokane in 1980 and was the first surgeon to do many of the more complex cardiac shunts and repairs in children. Dr. Leonard recruited two excellent congenital heart surgeons, Dr. Leland Siwek and Dr. Neil Worrall who had their training with Dr. Aldo Castaneda and Dr. John Mayer of Boston  Children's Hospital.

While in Spokane, Dr. Leonard has been President of the American Heart Association and the Spokane Surgical Society as well as Chairman of the Heart Institute of Spokane. Through 1990 Dr. Leonard, Dr. Wes Allen & Dr. Eric Johnson were involved in 5 trips to Ethiopia to donate heart surgery in hundreds of children that would not have received these operations.