Few studies have been carried out regarding preoperative chemotherapy utilized in the treatment of primitive neuroectodermal tumors/medulloblastomas (PNET/MB). In this paper, the authors report 3 cases of children under three years of age, with a presumed diagnosis of PNET/MB, who were preoperatively treated with chemotherapy consisting of high doses of carboplatin alone. The treatment improved the childrens' clinical condition prior to surgery and facilitated tumor removal, resulting in partial regression of the tumor. The preoperative single-drug therapy did not affect the histological diagnosis or prevent the presence of an effective degree of tumor sensitivity to the drug. All three children are still disease-free, after a mean follow-up period of 42 months.