Much of the literature on tumors arising in the setting of chronic epilepsy focuses on children. This study reviewed 1 institution's 141-patient experience with tumors in adults arising in this clinical setting. The majority of tumors (71.6%) arose in the temporal lobe. The most common tumor types encountered included ganglioglioma (n = 38), low-grade fibrillary astrocytoma (n = 24), and low-grade oligodendroglioma (n = 22). Coexistent focal cortical dysplasia (type IA) was identified in 15 cases (10.6%). The largest group of tumors in adults were World Health Organization (WHO) grade II neoplasms compared with WHO grade I tumors in children. Gangliogliomas are the most commonly encountered neoplasms. Coexistent focal cortical dysplasia may be observed in a significant minority of tumors, suggesting a possible developmental origin for some of these neoplasms.