OBJECTIVES To compare the efficacy and safety of transurethral microwave thermotherapy (TUMT) with ProstaLund Feedback Treatment, using the CoreTherm device, with transurethral resection of the prostate (TURP) 5 years after treatment. METHODS This prospective, randomized, multicenter study was conducted at 10 centers in the United States and Scandinavia. A total of 154 patients with benign prostatic hyperplasia were randomized to TUMT or TURP in a 2:1 ratio. Patients were followed up at 3, 6, 12, 24, 36, 48, and 60 months after treatment. The intermediate results at 12 and 36 months have been previously reported. The treatment outcome at 5 years was evaluated with the International Prostate Symptom Score (IPSS), quality of life question (QOL), peak urinary flow rate (Qmax), postvoid residual urine volume, and prostate volume. The CoreTherm device differs from other microwave devices in that the intraprostatic temperature is constantly measured during the procedure to guide the treatment. RESULTS Of the 154 patients, 66% completed the 60 months of follow-up. Statistically significant improvements in the TUMT and TURP groups were observed for IPSS, QOL, and Qmax at 60 months. The average values for the TUMT group were an IPSS of 7.4, QOL score of 1.1, and Qmax of 11.4 mL/s. The values for the TURP group were IPSS of 6.0, QOL score of 1.1, and Qmax of 13.6 mL/s. No statistically significant differences were found in any of these variables between the two treatment groups. In the TUMT group, 10% needed additional treatment versus 4.3% in the TURP group. CONCLUSIONS The clinical outcome 5 years after TUMT using the CoreTherm device was comparable to the results seen after TURP. The safety of TUMT using the CoreTherm device compared favorably with that of TURP.