Objectives. To report our early experience using transurethral microwave thermotherapy (TUMT) to treat patients with nonbacterial prostatitis (NBP) and prostatodynia. Methods. Nineteen patients with NBP (symptoms, negative cultures, no response to antibiotics, leukocytosis in expressed prostatitic fluid) and 5 patients with prostatodynia (symptoms, negative cultures, no response to antibiotics, no leukocytosis in expressed prostatitic fluid) were treated with TUMT at interstitial temperatures of 45 degrees to 60 degrees C for hour. Response was assessed by a consistent symptom severity index and global assessment of symptoms. Results. A marked and significant early (3 months) favorable response was noted in nearly one half of the NBP group but little benefit was found in the prostatodynia group. The treatment was associated with few adverse experiences. Conclusions. TUMT appears to be a potentially effective therapy for NBP, but its real efficacy as well as the durability of the response needs to be confirmed with a randomized double-blind sham-controlled trial.