This prospective, randomized, placebo-controlled trial aimed to investigate the efficacy of laser therapy in the treatment of carpal tunnel syndrome (CTS). Low-level laser therapy (LLLT) has been found to have positive effects in the treatment of CTS and various musculoskeletal conditions. A total of 81 patients were included in this study. Diagnosis of CTS was based on both clinical examination and electromyographic (EMG) study. Patients were randomly assigned into two groups. Group 1 (n = 41) underwent laser therapy (7 joules/2 min) over the carpal tunnel area. Group 2 (n = 40) received placebo laser therapy. All patients received therapy five times per week, for a total of 10 sessions. Patients also used a wrist splint each night. Patients were assessed according to pain, hand-pinch grip strength, and functional capacity. Pain was evaluated by Visual Analog Scale (VAS; day-night). Hand grip was measured by Jamar dynometer, and pinch grip was measured by pinchmeter. Functional capacity was assessed by a self-administered questionnaire for severity of symptoms. The mean age of the patients (70 women, 11 Men) was 49.3 +/- 11.0 (range, 26-78). After therapy there were statistically significant improvements in VAS, pinch grip, and functional capacity measurement in both groups (p < 0.001). Hand grip was found to have been improved in the laser group. In EMG, there were statistically improvements in sensory nerve velocity, and sensory and motor distal latancies in the laser group (p < 0.001). Only sensory nerve velocity was meaningful in the placebo group. In using LLLT, (1) there was no difference relative to pain relief and functional capacity during the follow-up in CTS patients; (2) there were positive effects on hand and pinch grip strengths.