Of 435 patients treated with local hyperthermia to the prostate 27 had 29 complications, for an over-all complication rate of 6.6%. Urinary tract infections (7 cases), hematuria (6), and epididymitis (2) accounted for roughly half of the complications and could be attributed to the insertion of a catheter rather than the treatment itself but this remains to be proved. Most of the complications occurred within the first 3 treatment sessions. Despite the complication, 9 patients continued and completed the treatment course. Mean age of the study group was 73 +/- 8.3 years. Given the age of these patients, high incidence of accompanying diseases and low rate of complications, local hyperthermia should be considered a viable low risk treatment option in patients with benign prostatic hyperplasia.