Subjects with an open bite and an atypical swallowing pattern before (n = 20) and after (n = 10) orthodontic treatment and subjects with a normal swallowing pattern (n = 15) were examined. The electromyographic (EMG) activity of the upper and lower lips in the region of the modiolus and of the mentalis, masseter and temporal muscles was evaluated during the swallowing of saliva and of water and after the chewing of peanuts as well as during maximal biting in intercuspal position. During swallowing the atypical swallowers exhibited larger EMG activities of the perioral muscles and smaller EMG activities of the masticatory muscles than the control subjects. During maximal biting in intercuspal position, major EMG activity of the masseter and temporal muscles and minor EMG activity of the perioral muscles were recorded in both groups. No normalization of the electromyographic swallowing pattern could be observed during orthodontic treatment (closure of the open bite).