Urethral irregularity (impeding catheterization) and failure to achieve continence are common complications in surgery for urinary incontinence. We describe a surgical technique using an anterior bladder wall flap that is sutured to the posterior wall in an onlay fashion creating a flap valve mechanism. Experimental work in dogs demonstrated a significant increase in the leak point pressure in the surgical group when compared to controls (p = 0.019). Voiding cystourethrography and bladder inspection demonstrated an anterior flap valve with no fistula formation in all animals. Histological examination showed a viable anterior bladder wall flap in all cases. This technique was then applied to 6 patients with neurogenic bladder and low urethral resistance that failed to resolve with medical treatment. Urinary continence was achieved in 4 patients. In 1 patient a vesicourethral fistula developed 3 months postoperatively, since the mother failed to catheterize for 12 hours. This technique is a useful alternative in the treatment of urinary incontinence.