Over a period of 5 years, 34 pediatric patients underwent stereotactic surgery for deep-seated brain lesions: 32 patients proved to have a brain tumor, and in 2 cases the lesion was not tumoral; 15 patients with low-grade astrocytomas were treated with 125I interstitial radiotherapy. The importance of stereotactic surgery is emphasized because of its relative safeness, diagnostic reliability, and the possibility of eventual brachytherapy.