A prospective evaluation was done of 84 patients who were selected for transurethral prostatectomy based on the presenting symptoms and findings at cystoscopy. In addition, urodynamic studies were performed but the results were not made available to the urologist who selected the patients for surgery. Postoperative symptom analysis and repeat urodynamic examinations were done at 3 months in 68 patients and at 12 months in 50. There was no significant association between irritative symptoms and uninhibited detrusor contractions. Furthermore, no associations were identified between obstructive symptoms and infravesical obstruction as defined by urodynamic criteria. The study failed to identify a need for routine invasive urodynamic investigation of patients with benign prostatic hypertrophy.