Arthroscopic surgery has been reported to decrease pain in relation to the TMJ, improving maximal interincisal opening (MIO). The aim of the present study was to report the clinical outcome of arthroscopic surgery for the treatment of chronic closed lock (CCL) of the TMJ. Five hundred consecutive patients (670 joints) with TMJ derangement who underwent arthroscopy between 1995 and 2004 were retrospectively analysed. All were classified as II-V according to Wilkes. Within the series, various arthroscopic procedures were performed. The inclusion criteria for CCL of the TMJ were met by 257 patients (344 joints). The mean age was 30.24 years; 237 (92%) were female and 20 (8%) male. Mean preoperative visual analogue scale score for evaluation of TMJ pain was 53.21+/-23.02. Mean MIO was 24.75+/-4.89 mm. Following arthroscopy, a significant decrease in TMJ pain was achieved (p<0.0001). For MIO, mandibular protrusion and lateral excursion movements, a significant increase in mean values was observed following surgery (p<0.0001). No statistical differences were observed between arthroscopic lysis and lavage and operative arthroscopy in relation to postoperative pain or MIO at any stage of the follow-up period. Arthroscopy should be considered as a first-line treatment for CCL of the TMJ.