The purpose of this study is to evaluate the safety and efficacy of 120-W potassium titanyl phosphate (KTP) laser vaporization in patients with benign prostatic hyperplasia (BPH) who also had cardiopulmonary diseases who were taking long-term anticoagulants and were at high risk of bleeding complications. The prospective study included 188 patients with severe lower urinary tract symptoms who underwent 120-W KTP laser vaporization of the prostate. All patients were at high cardiopulmonary risk, having presented with an American Society of Anesthesiology score of 3 or greater. Of those, 45 patients were taking oral anticoagulants, and 1 had a severe bleeding disorder. BPH was successfully treated with 120-W KTP laser vaporization in all patients. Mean preoperative prostate volume +/- SD was 66 +/- 23.1 ml, and mean operative time was 50.8 +/- 15.5 min. There were no major complications intraoperatively or postoperatively, and no blood transfusions were required. Postoperatively, only 14 patients (7.4 %) required bladder irrigation. Average catheterization time was 1.9 +/- 1.5 days (range, 1-5 days). Three patients required reoperation due to enlarged prostates from residual adenoma. At 3-, 6,- 12-, and 24-month follow-ups, mean urinary peak flow increased from 8.0 +/- 3.6 ml/s to 19.1 +/- 5.6, 19.2 +/- 4.7, 19.1 +/- 4.65, and 19.2 +/- 4.34 ml/s, respectively. Mean International Prostate Symptom Scores decreased over time, from 25.6 +/- 5.1 (3 months) to 9.4 +/- 2.8, 7.05 +/- 1.46, 6.24 +/- 1.36, and 6.20 +/- 1.32 (24 months), respectively. 120-W HPS KTP laser vaporization is a safe and effective treatment option in BPH patients at high risk and those on anticoagulation therapy who have severe LUTS secondary to BPH.