From February 1990 through May 1991, 37 patients with benign prostatic hyperplasia were treated by transurethral hyperthermia according to two different protocols. In group 1, 10 patients with an indwelling catheter underwent six one-hour sessions twice a week for three weeks, at a temperature of 43-degrees-C. The 27 patients from group II (11 with indwelling catheter) had two sessions of two hours each for one week, at a temperature of 44.5-degrees-C. Prostatic volume, Madsen symptom score, two estimates of peak flow, average flow, and residual urine measurements were recorded before treatment and one week, one month, six months, and one year after completing the sessions. Hyperthermia was applied through a metal ring, which was used both for heating and temperature control, mounted on a 16-F Foley-Tieman-like catheter. The follow-up period was five to fifteen months. From those who had an indwelling catheter, 5 of 10 patients (50%) from group I and 8 of 11 patients (72.7%) from group II regained spontaneous micturition and continued to void satisfactorily throughout the follow-up period. Nine of 16 patients without catheter (56.3%), showed objective and subjective improvement. Transurethral hyperthermia is a new, simple, noninvasive, and well-tolerated method for the treatment of benign prostatic hyperplasia.