Complications associated with enterocystoplasty include mucus production, electrolyte abnormalities, infections, stones and cancer at the vesicoenteric anastomosis. Removal of the intestinal mucosa with subsequent urothelialization may obviate these problems. We describe a unique approach whereby photodynamic therapy is used to de-epithelialize an ileal segment before augmentation. Enterocystoplasty was performed in 32 female Fischer 344 rats using a 1.5 cm. patch of terminal ileum. Of the 32 rats 24 survived at least 6 weeks before euthanasia. The experimental group (10 rats) received hematoporphyrin derivative intravenously 24 hours before surgery. The ileal patch was treated with red light for 20 minutes and then used for augmentation. There were 3 control groups, including 1 group of 5 rats that underwent augmentation alone, while the other 2 groups were augmented but received either light treatment (4 rats) or hematoporphyrin derivative (5 rats). Histological analysis revealed urothelialization of the augments treated with hematoporphyrin derivative and light, which did not occur in the controls. The preoperative and postoperative bladder capacities increased substantially in all groups. Mucus production and bacterial colonization were reduced while stone formation increased in the treated animals.