PURPOSE: External sphincterotomy is an accepted option for treating patients with detrusor-sphincter dyssynergia. However, long-term outcome data are limited. We ascertained the outcome of treatment results for this procedure. MATERIALS AND METHODS: A database was reviewed for patients undergoing external sphincterotomy at a large tertiary referral spinal injuries center. RESULTS: For 84 primary sphincterotomies the mean duration of successful outcome was 81 months. A second procedure was required in 30 patients and mean duration of success thereafter was 80 months. Recurrent symptomatic episodes of urinary tract infection, recurrent detrusor-sphincter dyssynergia or upper tract dilatation eventually ensued in 57 of 84 patients (68%). Renal failure did not develop in any patients. CONCLUSIONS: External sphincterotomy protects the upper renal tracts and provides extended periods of satisfactory bladder emptying. However, it may require ongoing revision and should potentially be regarded as a staged intervention.