Fifteen patients with significant bladder outlet obstruction secondary to benign prostatic hyperplasia (BPH) were entered in a Phase II open pilot study designed to evaluate the effectiveness of a low-power-slow-heating (15 W x 180 seconds) laser regimen. Laser prostatectomies were performed with a right-angle firing neodymium:YAG laser fiber. Perioperative morbidity was minimal. Nine patients (60%) were able to void on their own within 72 hours after the procedure. The mean postoperative need for catheter drainage was 3.8 days (range 1 to 12). With a mean follow-up of 5 months (range 3-15 months), the improvement of the mean peak urinary flow rate was from 12.8 to 29 mL/sec, the mean postvoiding residual volume was reduced from 100 to 35 mL, and the AUA Symptom Score improved from 28.5 to 6. None of the patients required retreatment, and all the patients were pleased with the outcome. These results suggest that the laser regimen used in our study is safe and effective for the treatment of BPH. © 1994, Mary Ann Liebert, Inc. All rights reserved.