His father, Robert, was a butcher, and his mother, Verna McClelland née Nelson, worked for a federal relief agency.
After completing a residency at Parkland Memorial Hospital, he was hired as a faculty member at the University of Texas Southwestern Medical Center.
In September 2007, he was appointed Professor Emeritus of Surgery at the UT Southwestern Medical Center, remaining involved in medical-student education.
[5] On November 22, 1963, McClelland was working at Parkland Memorial Hospital in Dallas, Texas, when President John F. Kennedy was brought in grievously injured.
Along with Tom Shires, McClelland worked unsuccessfully to save Oswald's life, as he was pronounced dead two hours after being shot.