Question To assess the effectiveness of low level laser therapy (LLLT) in the treatment of rheumatoid arthritis (RA). Data sources MEDLINE, EMBASE and The Cochrane Controlled Trials Register (CENTRAL) up to June 2005. Reference lists from relevant articles were scanned. Relevant studies were also traced by contacting experts. Study selection Randomised controlled trials of patients with RA which compared LLLT with other treatments or placebo laser therapy. Data extraction Methodological quality was assessed independently by two reviewers according to predefined criteria (Jadad scale), which included the appropriateness of randomisation, appropriateness of blinding, and description of dropouts and withdrawals. Results Six trials with a total of 222 patients were included. Five trials were placebo-controlled, while one trial used the opposite limb as a control. The median methodological quality was 3 (range 1–5). The included patients were adults with morning stiffness that ranged from 60 to 90 minutes. For five of the six trials the schedule of treatment was 2–3 sessions per week for 3–4 weeks. Four of the five placebo-controlled trials found a significant difference in pain in favour of the LLLT group. Weighted Mean Difference for the three trials using a 0–10 point visual analogue scale was 1.10 cm (95% CI 0.39 to 1.82). Statistically significant improvements were also found for tip to palm flexibility with a difference of 1.3 cm (95% CI 0.9 to 1.7) (two trials), and morning stiffness duration with an improvement of 27 minutes (95% CI 3 to 52) (three trials). In two trials patients were followed up three months after the end of treatment. No significant benefits of LLLT were evident at this time. The trial which used the opposite limb of the same individual as a control did not find any improvement in laser-treated hands. Conclusion This review clearly indicates that low level laser therapy decreases pain and morning stiffness in people with rheumatoid arthritis. It does not appear, however, to have long-lasting effects. Most of the studies tested laser therapy on the hand, so it is not clear whether laser therapy would affect other joints of the body the same way.