OUTLINE: This is a multicenter study. Patients are stratified according to disease type (glioblastoma multiforme (closed to accrual as of 05/31/2001) and gliosarcoma (closed to accrual as of 05/31/2001) vs anaplastic astrocytoma, anaplastic oligodendroglioma, and mixed malignant glioma). Patients receive oral fenretinide twice daily during weeks 1 and 4. Treatment repeats every 6 weeks in the absence of disease progression or unacceptable toxicity. Quality of life is assessed at baseline and then before each course of chemotherapy. Patients are followed every 3 months.