The perception of jaw position, measured as the ability to produce a predetermined mandibular posture repetitively, was recorded under different experimental conditions. A control group of asymptomatic subjects was tested before and after anesthesia of the TMJs and after fatique of the masticatory muscles. Groups of patients with craniomandibular disorders of arthrogenic or myogenic origin were also tested. None of the experimental variables affected position perception, and the patient groups did not differ from each otehr or the normal group in perception of jaw position. The possible clinical value of such recordings in differential diagnosis is therefore open to question.