Nephrogenic adenoma, an unusual proliferative lesion, often occurs in association with chronic inflammation of the bladder and is rarely found in children. Two cases are reported, one occurring in a young child born with bladder exstrophy, and one in a young female, with both interstitial cystitis and chronic use of immunosuppressive therapy. We believe these are the first case reports of nephrogenic adenoma occurring in this specific clinical setting.