Nd:YAG laser ablation of the endometrium has become an established procedure for the treatment of menorrhagia. Early studies utilized only half the 100-120 W available from commercially produced lasers. A preliminary in vitro study was done to measure the depth of coagulation caused by the Nd:YAG laser. Fifty watts applied with the contact or noncontact technique reached a depth of 3-4 mm, while 4-5 mm was reached using 100-120 W in the noncontact mode. Thirteen patients underwent endometrial ablation using the Nd:YAG laser at 100-120 W. The mean operating time was 31 minutes. All the patients were available for follow-up, and all had excellent results.