Artificial sphincter models AS791 and AS792 were used to treat 36 male and 7 female patients with urinary incontinence. Satisfactory results were obtained in 72% of the patients. Of 100 surgical procedures performed to achieve these results 61 were planned procedures (initial implantation and delayed activation) and 39 were revisions required to improve continence, change mechanically failing devices or remove eroded sphincters. From our study 3 major problems with the artificial sphincter are apparent: 1) stress incontinence, which was present in 55% of the patients with bulbous urethral sphincter compared to 21% with sphincters located at the bladder neck, 2) erosions, which appear to be related to balloon pressure used and location of the artificial sphincter (there seems to be a higher incidence of erosions when the bulbous urethral site is used with balloon pressure greater than 80 cm water) and 3) mechanical failures of the device, which accounted for 41% of the unplanned operations in our series. These 3 major problems are reviewed, the possible etiology of persistent stress incontinence is discussed and possible ways to avoid these complications are suggested.