In 17 patients, 2-16 years old, the clinical and neuroradiological data were unable to give clear-cut information regarding the histology of deep brain neoplasms. The lesions were located within the brain stem in two cases, in the pineal region in two cases, within the third ventricle in two cases, in the sellar and parasellar area in three cases, in the basal ganglia and thalamic region in seven cases, and in the fronto-callosal region in one case. In these patients, serial stereotactic biopsies were performed with the guidance of CT scan in order to assess the nature and the real boundaries of the growths. The choice between conservative or surgical treatment was made after the established histological findings became available. The operative technique of stereotactic biopsy is briefly described and the value of this method is stressed in the treatment of brain tumors in children.