We report for the first time a measured volumetric reduction of a choroid plexus carcinoma utilizing preoperative chemotherapy. Histologically proven choroid plexus carcinoma was diagnosed in a fifteen month old female. She was treated with three courses of chemotherapy including etoposide (VP16), cyclophosphamide, vincristine, and cisplatin. Computer-assisted three dimensional reconstruction of the tumor volume was performed prior to and after three courses of chemotherapy. An overall reduction of 29.5% of tumor volume was accomplished preoperatively. Staged surgical procedures resulted in a complete resection of her lesion and she has remained disease-free for 31 months. A volumetric measurement as a response to preoperative chemotherapy may prove valuable in determining future optimal treatment regimens for choroid plexus carcinoma of childhood.