PURPOSE: Fistula formation between the seminal, vesicles and a pelvic abscess after abdominal perineal resection for recurrent rectal cancer is reported in a 32-year-old male previously treated with low anterior resection, chemotherapy, and radiation. METHODS: The case history was reviewed for clinical presentation, radiologic studies, and laboratory data. RESULTS: Successful management of this previously unreported complication included percutaneous abscess drainage, antimicrobial therapy, and oral administration of Proscar(R) (Merck, Sharpe and Dohme, Rathway, NJ). CONCLUSION: Multiple factors predisposed this patient's development of a seminal vesicle fistula. These include extensive scarring from previous surgery, pelvic radiation, and an immunologically depressed status. The efficacy of Proscar(R) in the successful management of this case remains unknown.