One hundred and fifty patients with symptomatic benign prostatic hypertrophy (BPH) underwent transurethral microwave thermotherapy (TUMT). The single 1-hour TUMT session in the clinic was well tolerated and without significant adverse events. The mean Madsen urinary symptom score declined from 11.3 to 2.1 with a concomitant 54% increase in peak urinary flow rates by 4 months. Of the 22 patients with catheter-dependent urinary retention, 91% became catheter free. These early results appear to establish TUMT as an effective treatment of symptomatic BPH.