Ruff played his junior hockey in the Western Hockey League with the Lethbridge Hurricanes. In 1990, he was selected by the St. Louis Blues 96th overall of the 1990 NHL Entry Draft. Ruff made his firsts arms as a pro with the Peoria Rivermen, affiliate of the Blues, of the International Hockey League in the 1991 IHL playoffs. In 1991-92, Jason joined the Rivermen full-time. He would collect a good 72 points in 67 games in his rookie season. He split the next season between the Rivermen, the Atlanta Knights, the St. Louis Blues and the Tampa Bay Lightning. Over the course of that season and the next one, he would play 14 NHL games, scoring thrice and adding as many assists. That, however, would be all the NHL action Ruff would see in his career. He spent the next five seasons in the IHL with