Arthroscopic, clinical, and imaging observations were compared in 80 temporomandibular joints with suspected internal derangements. Rating scales were developed for assessment of the key arthroscopic findings of "roofing," vascularity, redundancy, articular surface condition, adhesions, and disc function. Clinical and imaging findings were correlated with the rated arthroscopic findings. The degree of roofing was found to have a significant relationship to disc quality and function. Arthroscopy completed the diagnostic picture in these cases and provided detailed information on the joints that was not elicited from clinical findings or imaging studies.