Aim : We evaluated the long-term results of transurethral interstitial laser coagulation in the treatment of benign prostatic hyperplasia (BPH) with up to 9 years of follow up at the Kurashiki Central Hospital and determined the patient characteristics that predict a favorable outcome. Methods : From December 1993 to May 1997, a total of 82 patients were enrolled in the present study. Subjective and objective voiding parameters were collected from medical records and a selfadministered questionnaire was sent to the patients. Kaplan-Meier plots were constructed to assess the risk of retreatment.Results : The mean follow-up period was 48.4 months (range, 3-108 months). A total of 59 patients (72%) did not need any additional treatment at 12 months and 30 patients (37%) did not require additional treatment during the entire follow-up period. A total of 29 patients (35%) were retreated during follow-up. Transurethral prostate resection (TURP) was performed in 18 patients (22%). The remaining 11 patients (13%) were offered additional pharmacotherapy. The minimum and median retreatment-free durations were 3 and 14 months, respectively. Seven patients died and 17 were lost to follow-up. Men aged 71 years or older had greater likelihood of requiring retreatment than those younger than 71 years ( P = 0.0397). No significant differences were noted in the other baseline characteristics. Among postoperative parameters, a rate of decrease of the International Prostate Symptom Score of the patient of lower than 60% and a rate of decrease in patient quality of life of lower than 50% at 3 months were associated with greater likelihood of retreatment ( P = 0.0083 and P = 0.0006, respectively). Conclusions : Interstitial laser coagulation is effective for the treatment of BPH. Good long-term results and an acceptably low retreatment rate render this modality an effective alternative to TURP, especially for younger patients. Short-term improvement of subjective symptoms was predictive of favorable long-term outcome.