Characteristic alterations of urethral pressure and length occur in patients with stress urinary incontinence. Urodynamics in this group of 50 patients revealed a significant decrease in urethral functional length under the stress of bladder filling and change of position from supine to sitting. A decrease in urethral closure pressure was present in individual patients and was significant. All patients with stress urinary incontinence demonstrated a decreased ability to voluntarily increase urethral pressure and also had evidence of pressure equalization on Valsalva maneuver and coughing. Cough pressure profiles also demonstrated equalization of urethral and bladder pressures. These profiles also were performed in a subgroup of 12 patients with genuine stress incontinence after treatment of incontinence by retropubic urethropexy. These profiles became normal after surgery and correlated with the clinical cure of stress urinary incontinence.