Background and Objectives: Transurethral electrovaporization of the prostate (TVP) has been utilized increasingly in the therapeutic management of benign prostatic hyperplasia (BPH). The temperature profile within both prostatic and periprostatic tissue has been presented as a parameter of safety in various preliminary studies. This prospective study measured interstitial temperature during TVP in both the prostate and the surrounding tissue of 18 men. Methods: These 18 men undergoing TVP had three interstitial thermocouple probes placed under ultrasound guidance. Probes were positioned in the rectal wall and at the 5 and 7 o'clock position of the prostate capsule. A fourth probe was placed within 1 mm of the area of vaporization to determine 'lesion' temperature. Temperature was measured at baseline and at 15-minute intervals as TVP was performed utilizing the VaporTrode at 240 to 280 W with a Valley Lab Force 40 generator. Results: The maximum temperature variability was 1.9°C. The temperature within 0.5 mm of the area of vaporization was > 100°C. These results were independent of the temperature of the irrigating solution. Conclusions: These results provide compelling evidence that high vaporization temperatures do not affect surrounding prostatic tissue. In theory, the risk of injury to either the rectum or the neurovascular bundle during TVP should be extremely low.