The authors studied the long-term effect of transurethral microwave thermotherapy (TUMT) using the Prostratron device on 30 patients with symptomatic benign prostatic hyperplasia (BPH). The maximum power output was 45 W, and the temperature within the prostate was expected to rise above 45 degrees C. The efficacy was evaluated using a specially designed scoring system based on both subjective symptoms and objective findings. Assuming that more than a 25% reduction of the total score indicates "effective," 80%, 70%, 63%, and 57% of the treatments remained effective at 8 weeks, 6 months, 1 year, and 2 years after TUMT, respectively. There were no major complications associated with TUMT during the follow-up period. Our results indicate that TUMT is an effective and long-lasting (at least 2 years) nonsurgical treatment in approximately 60% of patients.