Although not uncommon in adults, bladder tumors are rare in children. In addition, the histologic types of tumors seen in the pediatric population differ from those seen in adults. Although rhabdomyosarcoma is the most common pediatric bladder tumor, many other benign, malignant, and reactive lesions can be encountered. All may present clinically as a mass or polyp in the bladder. This study was designed to describe the pathology and patient demographics of pediatric bladder masses, because there are few studies describing these entities. Retrospectively reviewing our experience over a 21-year period, we identified 98 specimens from 65 patients with polyps or masses in the urinary bladder. As expected, the most frequent diagnosis was rhabdomyosarcoma. This was followed by fibroepithelial polyp and a variety of additional nonurothelial tumors. Only 7 urothelial tumors were identified, including 1 low-grade papillary urothelial carcinoma. Inflammatory lesions, such as cystitis cystica and nephrogenic adenoma, were invariably associated with an irritating factor when a history was provided. Our findings emphasize that diagnoses made in the pediatric urinary bladder are distinct from those in adults, although a wide variety of lesions may still be seen.