BACKGROUND Temporomandibular joint disorders are important oral health problems, reducing the quality of life of sufferers. It has been estimated that approximately 20% to 30% of the adult population will experience temporomandibular joint dysfunction. Arthrocentesis and lavage has been used to treat temporomandibular joint disorders for about 10 years, but the clinical effectiveness of the therapy has not been summarized in the form of a systematic review. OBJECTIVE To assess the effectiveness and complications of arthrocentesis and lavage for the treatment of temporomandibular joint disorders compared with controlled interventions. METHODS The Cochrane Oral Health Group's Trials Register (to August 2009), CENTRAL (The Cochrane Library 2009, Issue 3), MEDLINE (1950 to August 2009), EMBASE (1980 to August 2009), OpenSIGLE (to August 2009), CBMdisc (1981 to 2007 (in Chinese)) and Chinese Medical Library were searched. All the Chinese professional journals in the oral health field were handsearched and conference proceedings consulted. There was no language restriction. METHODS All randomised controlled trials (RCTs) (including quasi-randomised clinical trials) aiming to test the therapeutic effects of arthrocentesis and lavage for treating temporomandibular joint disorders. METHODS Two review authors independently extracted data, and three review authors independently assessed the risk of bias of included trials. The first authors of the selected articles were contacted for additional information. RESULTS Two trials, at unclear to high risk of bias, were included in the review. The two trials, including 81 patients with temporomandibular joint disorders, compared arthrocentesis with arthroscopy. No statistically significant difference was found between the interventions in terms of pain. However, a statistically significant difference in favour of arthroscopy was found in maximum incisal opening (MIO) (weighted mean difference of -5.28 (95% confidence interval (CI) -7.10 to -3.46)).Mild and transient adverse reactions such as discomfort or pain at the injection site were reported in both groups. No data about quality of life were reported. CONCLUSIONS There is insufficient, consistent evidence to either support or refute the use of arthrocentesis and lavage for treating patients with temporomandibular joint disorders. Further high quality RCTs of arthrocentesis need to be conducted before firm conclusions with regard to its effectiveness can be drawn.