We report here the case of a 29-year-old woman with cerebellar glioblastma. In the present case, tumor lesions were observed in each cerebellar hemisphere. The left-side lesion was diagnosed as glioblastoma, and the right-side lesion as malignant astrocytoma by histopathology. Immunohistochemistry revealed that the tumor cells of the left-side lesion was positive for p53, whereas epidermal growth factor receptors (EGFR) were negative in tumor cells from both sides. Genetic alterations were investigated using a genome DNA microarray (GenoSensor Array 300), which has led us to define this tumor as a secondary glioblastoma. The clinical presentation and genetic findings of this relatively rare entity are discussed.