&NA;The symptoms and clinical courses of 4 patients with neurofibromatosis and lesions of the brain stem identifiable on computed tomographic and/or magnetic resonance imaging scans are described. Two patients underwent biopsy and both had low‐grade astrocytomas with no evidence of anaplasia. Both received radiation and chemotherapy. The other 2 patients have been monitored without biopsy or treatment. Three patients are alive and clinically stable, having been followed up for an average of 4 years; neuroimaging studies have shown no change in their tumors. The fourth patient died of a supratentorial primitive neuroectodermal tumor. Imaging studies had shown no change in his brain stem lesion, which at autopsy was found to be a focal collection of fibrillary astrocytes. These data suggest that some patients with brain stem lesions and neurofibromatosis may have a prognosis distinctly different from that of the typical patient with a brain stem glioma. We recommend caution against aggressive operative and adjuvant therapy for brain stem lesions in patients with neurofibromatosis, unless progression of the lesion is documented clinically and/or by imaging. (Neurosurgery25:959‐964, 1989)