Ahmad Starks added 14 points and nine rebounds for Oregon State (4-1), which also got 11 points and 10 rebounds from Eric Moreland.
Antonio Biglow scored 14 points and Flavien Davis had 12 points and nine rebounds for Montana State (1-3).
The Bobcats came within 58-51 with 11:13 remaining after Xavier Blount made a pair of free throws. The Beavers’ Olaf Schaftenaar answered with a 3-pointer to restore the double-digit lead.
Montana State came no closer than eight points after that. Oregon State went on to lead by as many as 18 points.