Fr the efficacy and saftey of the surgical manipulation in stapedotomy for otosclerosis, the author did such surgery using CO2 lair in 44 cases. postperative follow up (3-12 months) reveals that hearing mean gain is 31+75:8.2 dB and air-bone conduction gap is within 11, 25:6.6 dB. There is no significant change at 4000 Hz. The advantages of CO2 laser tenlque are summarized as follows: convenience for cutting posterior crus, less lime eonuming for penetration on thick footpkate or removal of occlusive slerotic plaque within the oval window niche, avoidance of footptate flatlng with slight fixation of fooplate, and rapid coagulation of residual stzpedia artery as well as no instrumental difficulties at some narrow spaces. Our results state that CO2 lair creates essntial improvement in the development of the stapedotomy in otosclerosis.