One complication of cutaneous ureterostomy is urinary stone formation, which may lead to recurrent pyelonephritis. Frequent catheter changes and the prophylactic administration of antibiotics are commonly used to prevent stone formation. Cranberry products have been reported to inhibit stone formation in indwelling urethral catheters. We herein examined the inhibitory effects of a cranberry product on stone formation in a case of catheter occlusion due to stone formation after cutaneous ureterostomy. The results obtained indicate the potential of cranberry products to prevent stone formation after cutaneous ureterostomy requiring catheter placement.