Twenty patients, aged 6 months to 20 years, with low-grade astrocytoma (LGA) participated in a chemotherapy trial of vincristine (VCR) and etoposide (VP-16). Fourteen children had recurrent progressive disease at entry on study. Prior treatment consisted of surgical resection alone (6), surgical resection and irradiation (4), surgical resection, irradiation and chemotherapy (2), surgery and chemotherapy (1), and irradiation and chemotherapy (1). Six patients were treated at initial diagnosis of LGA because they were less than 5 years old (5) or for a second primary tumor (1). Four recurrent patients and 3 newly diagnosed patients underwent surgical debulking of their tumors immediately prior to study entry. Tumors were located in the optic nerve/chiasm/hypothalamus (8), brain stem/cerebellum (4), cerebral hemispheres (3), midline structures (3), and spinal cord (2). The treatment plan administered in an out-patient setting consisted of weekly VCR 1.5 mg/m2 for 7 to 8 weeks and VP-16 100 mg/m2 for 5 days repeated every 6 weeks for a total of 18 months of therapy. Responses were evaluated by computerized tomography or magnetic resonance imaging. Of the 20 patients, 1 exhibited a partial response maintained for 12+ months, 3 exhibited minor responses maintained for a period of 10+ to 35 months, and 11 maintained stable disease for 10 to 42 months. Of the 11 patients with stable disease, 2 were withdrawn early from the study without further therapy. Five of the 20 patients developed progressive disease; for 4 of these 5, this occurred during the first course of therapy. Subsequently, these 5 died due to tumor.(ABSTRACT TRUNCATED AT 250 WORDS)