Purpose: The aim of this study was to identify the clinical baseline factors that affect failure of medical treatment(and especially surgical treatment) for benign prostatic hyperplasia(BPH) in spite of long-term medication. Materials and Methods: 802 men who were over 50 years of age with BPH were enrolled for this study. Patients were allocated to a medication group and a surgical treatment group(after having at least a 12 month duration of medication). We compared the differences between the two groups for their initial International Prostate Symptom Score(IPSS), the uroflowmetry, the prostate volume, the postvoid residual urine and the serum prostate specific antigen(PSA). Results: 397 patients had surgical treatment following medication due to BPH progression(acute urinary retention, aggravating LUTS) and 405 patients were given maintenance medical treatment during follow-up. Statistically significant differences were found in the IPSS(23.3±6.6 vs. 12.7±8.4), the prostate volume