The Trail Blazers won their eighth straight game, limiting the Bucks to 31 points in the second half.
Damian Lillard added 19 points for the Blazers, whose 6-1 road record is the best in the NBA.
Portland won despite shooting just 40 percent from the field. Aldridge and Lillard combined to hit 17-of-40 shots.
Milwaukee, which has lost six in a row, was led by 13 points from Luke Ridnour.