One hundred and two patients with benign prostatic hyperplasia were treated by transurethral radio-frequency thermotherapy (TURT) device (Thermex-II, Direx, Israel) with 47.5 ℃ in single session for 2 hours and 30 minutes from November 1992 to October 1993. Among them, 83 patients, who were followed up for more than 3 months were included in this study. Twenty-seven (32.5%) patients had a history of acute retention. Pretreated values of the mean Madsen-Iversen symptom score, maximum urine flow rate, postvoiding residual urine volume, prostate volume and prostate specific antigen (PSA) were 15.4, 6.5 ml/sec, 61.3ml, 43.2ml and 0.77 ng/ml respectively. Madsen-Iversen symptom score, maximum urine flow rate were measured at 2 weeks, 1, 3 and 6 months after TURT. The residual urine volume, prostate volume and PSA level were measured at 3 and 6 months after TURT. During the follow up, the symptom score started to decrease significantly at 1 month (9.9, p< 0.01) after TURT, and gradually decreased up to 6.9 at 3 months. The maximum flow rate showed initial significant improvement at 2 weeks (8.1 ml/sec., p< 0.01), but no significant interval change was observed thereafter. The residual volume decreased significantly at 3 months (41.3 ml, p< 0.01) and no decrement was noted until 6 months. Neither the prostate volume nor PSA value changed significantly at 3 or 6 months after TURT. The improvement, which was defined as a change of 50% or more in at least one of subjective or objective symptoms showed in 63.9% (53/83) at 3 months and 57.1% (32/56) at 6 months. Both subjective and objective improvements at 3 and 6 months after treatment showed in 24.1% and 19.6%, respectively.