Tonsillectomy is one of the most frequently performed surgical procedures in the otolaryngologic field, however, severe pain after tonsillectomy is still a major problem especially in adults. There are numerous trials and reports on reducing pain after tonsillectomy, and laser is one of those trials with various results. To clarify the tissue effects of using different lasers and to identify the better type of laser in the reduction of post-tonsillectomy pain, contact type KTP-532 laser and Nd-YAG laser were used with same contact fiber. Thirty consecutive adults or school-aged patients undergoing tonsillectomy were prospectively studied. Pain was measured by a visual linear analogue scale from the day of operation to the fourteenth postoperative day. The amount of laser energy (Joule) used for each tonsillectomy was compared between KTP-532 and Nd-YAG laser groups. The result showed no significant differences in postoperative pain and in total energy used for tonsillectomy between KTP-532 and Nb-YAG laser groups. These findings suggest that KTP-532 and Nd-YAG lasers produce similar tissue effects if they are delivered through the same contact fiber.