During a 3-year period starting in 1991, 49 patients with brain lesions underwent 50 stereotactic brain biopsy procedures. The average age was 46 years (range 4-74). Specimens were taken from various brain regions, particularly from the deep aspect of the cerebral hemispheres and midline structures. The pathologic entities included 27 gliomas (13 glioblastomas, 6 astrocytomas, 3 anaplastic astrocytomas, 1 pilocytic astrocytoma and 4 oligodendrogliomas), 5 lymphomas, 2 germinomas, 1 primitive neuroectodermal tumor, 2 metastatic tumors and 11 non-neoplastic lesions (4 demyelination, 2 infarcts, 1 hematoma, 1 brain abscess, 1 radiation necrosis, 1 Alzheimer's disease and in 1 case no diagnosis). The diagnostic success of the stereotactic brain biopsies in this series was 96% (in 98% of the patients). The mean hospital stay was 3 days. 1 patient with a multifocal bilateral glioblastoma died due to early postoperative hematoma of the basal ganglia (2%). Another 2 patients underwent craniotomy due to post-biopsy hematoma. They continued to suffer from hemiparesis after discharge. Transient Horner's syndrome was noted in 1 patient. Thus the permanent morbidity rate was 4%. We conclude that stereotactic brain biopsy can be performed relatively safely, has a high diagnostic yield, and facilitates planning of treatment.