Congenital intracranial tumors are rare. If such a lesion is detected before birth, it is usually an incidental finding on fetal ultrasonography. The definition of a "congenital" tumor is controversial. The authors report the case of a "definite" congenital glioblastoma multiforme (GBM) diagnosed with the aid of ultrasonography and fetal magnetic resonance (MR) imaging in the 37th week of gestation. Postnatal MR imaging revealed a massive tumor occupying the patient's left temporoparietooccipital area. Angiography was performed to assess vascularity and embolize the main feeding arteries. Surgery was performed, and the tumor was successfully excised completely.