Center Nikola Vucevic had 22 points and seven rebounds for a Bulls squad that lost for a ninth time in their last 12 games. It has left them in the No. 5 spot in the East after spending much of the season near the top of the conference.
The Bucks are going the other way, winning seven of their last 10 that has them sitting just two games behind conference-leader Miami with 10 games to go.
Milwaukee will host Washington on Thursday at Fiserv Forum.