A 6-month-old girl had a gradually increasing head circumference. A preoperative computed tomographic (CT) scan of the head revealed an enhancing calcified partially cystic right frontal mass that was removed through a right frontotemporal craniotomy. On microscopic examination, the tumor was composed of sheets of neurons in a glial background alternating with highly cellular anaplastic areas. The diagnosis of anaplastic ganglioglioma was made. The child has done well for the 20 months since the operation without any evidence of tumor recurrence on subsequent CT scans. Because of the immaturity of the child's developing central nervous system, we have elected not to initiate radiotherapy at this time. The pertinent literature regarding gangliogliomas is reviewed.