OUTLINE: A complete resection of tumor is performed on patients with low grade glioma with or without neurofibromatosis type 1. Surgery is reconsidered following tumor relapse, progression, or clinical deterioration. Every effort is made to obtain a biopsy from patients not receiving debulking surgery. Nonoperative patients and postoperative patients who are not candidates for second surgery receive chemotherapy or radiotherapy. Postoperative patients receive radiotherapy following surgical wound healing and within 28 days of resection. Children less than 5 years old receive chemotherapy first, then radiotherapy if the tumor subsequently progresses or recurs. All other patients receive radiotherapy, then chemotherapy. The latter treatment is conducted in the presence of tumor progression. Chemotherapy is given in 2 parts, first an initial intensive phase (phase 1), then a later continuation phase (phase 2). In phase 1, patients receive vincristine IV weekly for 10 weeks and carboplatin IV every 3 weeks. In phase 2, patients receive vincristine IV and carboplatin IV every 4 weeks for a total treatment time of 52 weeks. Chemotherapy continues until disease progression or unacceptable toxicity. Patients receive radiotherapy daily 5 times a week. Patients are followed every 3 months for 1 year, every 6 months for 1 year, and then annually for 3 years.