Gregg continued to be a solid contributor over the next few seasons for the Oilers as they dominated the NHL and won the 1985 Stanley Cup, although he would be slowed somewhat by injuries. However, hockey was still something of a temporary career for Gregg, and he was conflicted about when he should leave the sport and take up his medical career . He retired after the Oilers' disappointing loss in the 1986 playoffs, but changed his mind six weeks into the season and helped Edmonton win their third championship in 1986–87. He retired from professional hockey again for the 1987–88 campaign to enter a residency program in orthopedic surgery as well as represent Canada at the 1988 Winter Olympics, but re-joined Edmonton for the playoffs to win another Stanley Cup.