Peppers missed his third straight day of practice Friday because of a sprained MCL he suffered in Monday's loss at Detroit.
Also for the Bears, tackle Gabe Carimi and defensive tackle Matt Toeaina were ruled out for the Vikings game because of knee injuries. Carimi hasn't played since Week 2.
Peppers is in his second season with the Bears after playing his first eight with the Carolina Panthers. He has 12 tackles and two sacks in five games this season.
Bears wide receiver Earl Bennett is questionable for Sunday's game because of a chest injury suffered back in Week 2 at New Orleans.