The outcome of postsurgical pyuria in benign prostatic hypertrophy was studied in 87 patients, and the factors that might affect the outcome were determined. No significant differences were found between operation method and duration until normalization of pyuria, which was 75.5 +/- 46.0 days for transurethral resection of the prostate, 72.7 +/- 30.6 days for suprapubic prostatectomy and 69.3 +/- 32.7 days for retropubic prostatectomy. Prognostic factors were statistically analyzed preoperatively, at operation, and postoperatively. The definite prognostic factors were preoperative diabetes mellitus, preoperative pyuria, preoperative bacteriuria, and postoperative hypoproteinemia. The probable prognostic factors were old-age, preoperative indwelling catheters, heavy prostate tissue, postoperative bacteriuria, postoperative anemia and postoperative complications.