The 1989–90 OHL season was the tenth season of the Ontario Hockey League. The Toronto Marlboros become the Dukes of Hamilton. The Guelph Platers become the Owen Sound Platers. The Kingston Raiders are renamed the Kingston Frontenacs. The OHL Executive of the Year award is inaugurated. Fifteen teams each played 66 games. The Oshawa Generals won the J. Ross Robertson Cup, defeating the Kitchener Rangers.