Jamison started 5 for 5 and scored 12 of Washington's first 14 points, but made just one of his next five shots before halftime. He finished 9 for 15.
Chris Bosh, who made his debut Friday after sitting out all of training camp and Toronto's first two preseason games with a strained left hamstring, shot 2 for 7 and finished with eight points and four fouls in 19 minutes.
The Raptors were again without swingman Hedo Turkoglu, who is being rested and hasn't played in the preseason.
Sonny Weems started for Toronto but left late in the first with a sore left big toe and did not return.