A permanent cell line arising from a cerebellar medulloblastoma was established and its growth characteristics were investigated. Although the original tumor inoculum failed to take, the cultured cells were readily tumorigenic in nude mice and gave rise to rapidly growing tumors which could be easily subpassaged. The primary tumor showed evidence of both glial and neuronal differentiation, and retention of neuronal differentiation, albeit minimal, occurred in both the cultured neoplastic cells and the nude mouse tumors. Glial differentiation, on the other hand, could not be demonstrated. G-banding analysis of the chromosomes present in the cell line showed that they were exclusively human.