We report two cases of a recently isolated variety of astrocytoma, pleomorphic xanthoastrocytoma, affecting the cerebral cortex and meninges of children and young adults. The first tumor was localized in the left frontal lobe of a 9-year-old girl. The second appeared in the right parietal lobe of a 14-year-old girl. Both tumors displayed a pleomorphic cellular proliferation, with spindle-shaped and bizarre multinucleated giant cells, some positive for neutral lipids, with a prominent reticulin network and areas highly suggestive of malignant fibrohistiocytomas (fibroxanthosarcomas). The glial fibrillary acidic protein was demonstrated by the immunoperoxidase method in the cytoplasm of the giant and the spindle cells. Ultrastructural studies confirmed the glial nature of the tumor. This type of tumor seems to carry a much better prognosis than other tumors from which it has to be separated, e.g., glioblastoma and meningeal sarcomas.