Paris Lee added 10 points for Illinois State (13-4, 5-0), which has won six straight and is tied with Wichita State (15-3, 5-0) atop the conference.
The Redbirds opened the second half on a 22-11 run for a 50-44 lead with about eight minutes to play. The game was then scoreless until Phil Fayne's dunk stretched the lead to 52-44 with 5:34 left.
Mike Rodriguez made a layup and Sean O'Brien added a jump shot to pull the Salukis to 52-48 with four minutes left, but they didn't get closer.
O'Brien had 15 points and Armon Fletcher 12 for Southern Illinois (10-8, 3-2), which had its three-game win streak snapped.
