Juvenile granulosa cell tumor (JGCT) of the ovary has been reported to occur rarely in conjunction with Ollier's disease. We report a case of a 13-year-old girl who was noted to have a large abdominal mass at the time of excision of a symptomatic enchondroma of the right femur. Subsequent laparotomy at a tertiary care children's medical center identified a JGCT confined to the right ovary. Review of the literature reveals eight previous cases of JGCT in patients with Ollier's disease. The pathophysiology and possible common causes of both disorders is discussed.