Thirty women with urinary incontinence underwent detailed preoperative and postoperative clinical and urodynamic evaluation before and after the pessary test. The urodynamic changes observed with the pessary test (P less than .01) were very similar to those seen after corrective incontinence surgery. The pessary test differentiated patients with bladder instability from those complaining of stress urinary incontinence with a correctable anatomic defect. Pre- and postpessary test voiding urethrocystometry and uroflometry demonstrated absence of urethral obstruction to the free flow of urine. The pessary test is a simple, inexpensive, reliable diagnostic and prognostic tool. It simulates the results of anticipated incontinence surgery and restores continence without causing compression of the urethra as does the Bonney test.