OBJECTIVE The study aims to evaluate the efficacy of arthrocentesis in the treatment of internal derangement of the temporomandibular joint (TMJ). METHODS Thirty patients with TMJ internal derangement underwent arthrocentesis using saline. Pain using visual analog scale, maximum mouth opening, joint noises and mandible deviation were documented pre-operatively and post-operatively. Patients were followed for 1 year. Statistical analysis of pain was done by Wilcoxon signed Rank's test and dysfunction by students paired t test. RESULTS The mean pre-operative pain was 4.8 ± 2.65 and post-operatively at 1 year was 0.27 ± 0.45 with an average decrease of 4.72 (P = 0.000). The mean maximal mouth opening pre-operatively was 29.8 ± 2.35 mm and post-operatively 41.9 ± 2.48 mm at 1 year. The mean increase in the mouth opening was 12.1 ± 3.0 mm (P = 0.000). CONCLUSIONS Arthrocentesis is simple, minimally invasive procedure with less risk of complications and significant benefits in patients with TMJ internal derangement.