The prognosis in children harboring a glioblastoma multiforme (GBM) is usually poor. Few GBMs in children, however, seem to respond quite well to adjuvant chemotherapy. The biological basis for such chemotherapy sensitivity remains uncertain. In this paper the authors report the case of a 2-month-old girl with a histologically confirmed GBM (WHO Grade IV) in whom chemotherapy was accompanied by differentiation of the malignant primary tumor into a typical gangliocytoma (WHO Grade I) showing ganglioid differentiation and expression of neuronal markers synaptophysin, neurofilament, and NeuN as well as a low Ki 67/MIB-1 proliferation index. Array-comparative genomic hybridization did not reveal genetic alterations in either specimen. Even though the underlying biological mechanisms remain to be elucidated, closer examination of frequency and prognostic significance of neuronal differentiation in pediatric GBMs within ongoing and future clinical trials may be warranted.