The effect of low level laser (GaAs) on lateral epicondylitis was investigated in a double-blind, randomized, controlled study. Thirty patients were assigned equally to a laser (n = 15) or a placebo laser (n = 15) group. All patients received eight treatments and were evaluated subjectively and objectively before, at the end of, and four weeks after treatment. Patients also completed a follow-up questionnaire on an average of five to six months after treatment. A significant improvement in the laser compared to the placebo group was found on visual analog scale (p = 0.02) and grip strength (p = 0.03) tests four weeks after treatment. In this study low level laser therapy was shown to have an effect over placebo; however, as a sole treatment for lateral epicondylitis it is of limited value. Further studies are needed to evaluate the reliability of our findings and to compare laser to other established treatment methods.