The folate receptor is a membrane linked glycoprotein that participates in the cellular accumulation of 5-methyltetrahydrofolic acid, methotrexate and 5,10-dideazatetrahydrofolic acid. Relative receptor overexpression has been observed in several malignant cell lines and tissues. In this study we determined receptor expression using western blot analysis in primary pediatric malignancies involving the central nervous system. This study suggests that ependymoma tumors have a high frequency of receptor expression which may reflect a specific cytogenetic abnormality or the cellular origin of these tumors. The potential role in developing selective chemotherapy mediated by the folate receptor is also discussed.