We studied the 5-year long-term outcome of arthroscopic surgery, and also investigated whether outcome correlates with stage of internal derangement of the temporomandibular joint (TMJ). A consecutive group of 41 patients (56 joints) who had been followed up for between 3 and 5 years were involved in this study. The result was excellent in 22 patients (54%) and fair in 15 (37%). 7/14 were excellent and 5/14 were fair in stage III, 7/12 were excellent and 4/12 were fair in stage IV, and 8/15 were excellent and 6/15 were fair in stage V. Arthroscopic surgery of the TMJ is an effective and minimally invasive technique for various stages of internal derangement.