The temporomandibular joint (TMJ) is a synovial joint that responds to injury in a similar fashion to other joints in the body. A common adjunct in treating this joint is ultrasound. Some clinicians question the use of ultrasound over the TMJ for fear it might damage the periosteum. Therefore, 2,486 TMJ ultrasound treatments were evaluated retrospectively. Only 14 (.56%) of these reported an abnormal sensation. Only 10 of the 14 showed signs of periosteal ache. Since 2,472 reported no abnormal sensation, it was concluded that a protocol of 100 percent continuous ultrasound set at 1.25 W/cm2 for 3 minutes over the TMJ is tolerated well. J Orthop Sports Phys Ther 1992;15(5):206-208.