Gas in the joint space was observed in three patients with condylar fracture who were referred for CT examinations of the mandible. CT showed that the condylar fractures were non-open fractures. The gas was only observed in the intrajoint capsule of the temporomandibular joint (TMJ). Follow-up CT, 4 days after the initial CT, showed that the gas in the joint space was absorbed in one of three cases. In the non-open condylar fractures, the gas collection in the TMJ was considered to be a vacuum phenomenon due to the intact joint capsule of the TMJ on CT.