Assistant Mark Pittman will be the interim head coach for the rest of this season.
With the seventh defeat in their last eight games, 88-58 to Murray State on Wednesday, the Tigers' record dropped to 6-16 (4-8 OVC).
"We thank Coach Alexander for his service to the basketball program as head coach," said Athletic Director Teresa Phillips on the school's Web site after Friday's firing. "The program at this time, however, needs a new direction."
Alexander, who had an overall record at TSU of 67-107, had saved his job last year by advancing to the title game at the Ohio Valley Conference tournament. The Tigers' 2007-08 season ended with an 82-64 loss to Austin Peay in the title game, giving them a 15-17 overall record.