Two hundred patients with acute and chronic pain were treated with a low power laser and 115 patients among them were divided into several groups by their pathology and evaluated their response rate to the laser therapy was evaluated through follow-up study. 1) The ages of patients were between the early twenties and late sixties, and there was no differences between sexes. 2) Degenerative spondylosis and chronic lumbar sprain were the most common diseases among those patients. 3) The average duration of therapy was about 16 days and response to the therapy appeared from the fourth day of laser therapy. 4) Acute lumbar sprain and acute spinal compression fracture showed rapid response to laser therapy. 5) The spinal pathology group was the most common at 37.5% of cases and the response rate to laser therapy was the lowest at 58.7%. 6) The articular pathology group occupied 24.6% and the response rate was the highest at 81.3%. 7). The response rate of the posttraumatic and postsurgical pathology group was 76.5%. 8) The response rate of the tendinous and sports pathology group was 75%. 9) The response rate of the miscellaneous group was 66.7%. 10) The mean response rate of all patients was 71.6%.