Ependymoma, a common neoplasm in the central nervous system of children, expresses great variability of morphological appearances. Correlation with clinical behavior has been controversial in previous studies. In order to explore the potential value of DNA-flow cytometric analysis in predicting the clinical course of ependymomas in children, we studied 22 patients with this tumor, selected from two large pediatric institutions. In addition, a number of histologic features were reviewed, such as necrosis, mitoses, endothelial proliferation, cellularity, and pleomorphism. DNA analyses of paraffin-embedded tissue from these tumors showed 9 of 17 (53%) with DNA indexes less than 1.16 and 8 of 17 (47%) with DNA indexes above 1.16. Ten of 17 (59%) patients died, 2 (12%) were lost for follow-up, and 5 (29%) are alive. No statistical correlation was found between DNA index, outcome, and histology. In spite of the small sample size, our findings appear to support the general impression that ependymomas are morphologically highly variable tumors of potential aggressiveness without valuable prognostic histologic markers.