A few games into his third season with the Mooseheads, he tied a franchise record with five points in one game, an 11–3 victory over the Baie-Comeau Drakkar on October 9, 1998, then tied another record with four goals in a 6–1 defeat of the Drummondville Voltigeurs six nights later. However, he suffered a concussion early in the season which forced him out of the line-up for 28 games. Though he was limited to 31 contests in 1998–99, he scored 27 goals and 61 points. Tanguay finished his junior career as the Mooseheads' all-time leader in goals (101), assists (113) and points (214). In honour of his accomplishments, the team retired his #18 jersey in 2005.