OBJECTIVES: To report the safety and efficacy of the transurethral needle ablation (TUNA) procedure for the treatment of clinical benign prostatic hyperplasia (BPH). METHODS: One hundred thirty patients with BPH were enrolled in two identical protocols and treated by the TUNA procedure. Entry criteria included an American Urological Association symptom index (AUA SI) of 13 points or higher and a peak flow rate of 12 mL/s or less. Patients were followed up for 12 months. Efficacy parameters included the AUA SI, AUA problem index, BPH impact index (BPH II), quality of life (QOL) score, and peak flow rate. At each visit, side effects were elicited. Follow-up data are available for 93 patients at 12 months. All patients were given intraurethral lidocaine augmented by oral and/or parenteral sedation. No patient received spinal or general anesthesia. RESULTS: All patients tolerated the procedure well, and there were no deaths. Forty-one percent of patients (n = 53) had a catheter placed immediately after the procedure. At 12 months, the AUA SI had decreased from 23.7 to 11.9 (P < 0.0001) and the BPH II from 7.5 to 2.5 (P < 0.0001), whereas the peak flow rate had increased from 8.7 to 14.6 mL/s (P < 0.0001). Irritative voiding symptoms were noted in 20 patients (16%) at some point during follow-up. Two patients reported erectile dysfunction, and 1 reported retrograde ejaculation. CONCLUSIONS: In this prospective study of 130 patients with clinical BPH and lower urinary tract symptoms, TUNA provided substantive and lasting improvement according to AUA SI, BPH II, and QOL scores as well as peak flow rate over 1 year. The TUNA procedure was well tolerated, with few major side effects and complications noted. Longer follow-up is needed to document the maintenance of clinical benefit beyond 12 months.