The Salukis (11-15, 4-11 Missouri Valley), who snapped a seven-game losing streak in the series, scored the game's first 10 points, never trailed and shot 51.2 percent (22 of 43) from the floor.
Missouri State trailed by nine points at intermission but got within 40-38 midway through the second half. But the Bears then went scoreless for a stretch of 6:01, enabling Southern Illinois to take permanent control.
Anthony Beane scored five points and T.J. Lindsay hit a 3-pointer during a 10-0 run. Beane's three-point play made the score 50-38 with five minutes remaining, and Missouri State got no closer than six points the rest of the way.
Purdue coach Matt Painter says players haven't used the fifth-year graduate transfer rule for its true intent.
The dust has settled after players made their NBA draft decisions. Which college teams won? Which lost? Well, Villanova is pretty happy. USC, meanwhile, might not be as thrilled.
The 2017 recruiting class is short on point guards, with Trevon Duval leading only eight prospects from the ESPN 60 who are still available.