1998–99 Mount St. Mary's Mountaineers men's basketball team

The 1998–99 Mount St. Mary's Mountaineers men's basketball team represented Mount St. Mary's University during the 1998–99 NCAA Division I men's basketball season. The Mountaineers, led by head coach Jim Phelan, played their home games at Knott Arena and were members of the Northeast Conference. They finished the season 15–15, 10–10 in NEC play to finish in sixth place. They were champions of the NEC tournament to earn an automatic bid to the NCAA tournament. Playing as the No. 16 seed in the Midwest region, the Mountaineers lost to No. 1 seed and eventual Final Four participant Michigan State in the Round of 64.

Schedule and results
!colspan=9 style=| Non-conference Regular season

!colspan=9 style=| NEC Regular season

!colspan=9 style=| Northeast Conference tournament

!colspan=9 style=| NCAA tournament