Papillary glioneuronal tumors are a newly recognized type of brain neoplasm characterized by prominent pseudopapillary structures and glioneuronal elements. All prior cases have shown that these tumors have an indolent course. The authors present 2 patients with an aggressive variant of the tumor. The first patient had dissemination of her tumor and the second had local spreading. Therefore, the authors conclude that papillary glioneuronal tumors do not always behave in a strictly benign fashion.