High-grade astrocytomas comprise approximately 10% of intracranial tumors in children. A better prognosis in children than in adults has been reported for patients with these neoplasms, although the reasons for this survival advantage are uncertain. To determine whether any consistent factors were associated with long-term survival, we reviewed the records of 31 children with high-grade non-brain stem gliomas who were treated at our institution between 1975 and 1992. Histology was reviewed and classified according to the World Health Organization scheme, and neuroimaging studies were examined to determine the extent of resection, in both instances by individuals who were unaware of the patients' outcomes. The median overall survival for the 28 patients who survived the perioperative period was 18.5 months; 10 (36%) are currently alive, with a median follow-up of 70.5 months. The median progression-free survival (PFS) was 10.5 months; eight patients (29%) remain progression-free with a median follow-up of 78 months. The extent of resection at initial operation was associated most closely with PFS and overall survival as revealed by multivariate analysis. The 14 patients who underwent subtotal (< 90%) resection and the 7 who underwent near-total (90-99%) resection had median PFS of 5.5 and 11 months, respectively (P = 0.38), and overall survival of 10.5 and 25 months, respectively (P = 0.02). None of the seven patients who underwent gross total removal of tumor as confirmed by postoperative imaging had disease progression, with a median follow-up of 84 months (P < 0.0001). All of the tumors that underwent gross total resection were situated within the cerebral hemispheres; five of the seven patients had seizures as a presenting symptom. Both tumor location and seizures were significantly associated with outcome as determined by univariate analysis, but because of the overwhelming impact of resection extent on outcome, these factors were not independently associated with outcome as revealed by multivariate analysis. Histology was associated with outcome in the subgroup of patients with incompletely resected hemispheric tumors, in which children with anaplastic astrocytoma had a significantly better PFS than those with glioblastoma multiforme (P = 0.009). In summary, our results support the role of cytoreductive surgery in the treatment of cerebral hemispheric high-grade astrocytomas in children, which may encompass a biologically distinct group of tumors that, by virtue of their location and growth characteristics, are amenable to aggressive resection. The prognosis for children with deep-seated lesions and for those with subtotally resected hemispheric lesions is generally poor with conventional therapy.