Linear nevus sebaceous syndrome is a rare, congenital neurocutaneous syndrome comprising nevus sebaceous, seizures and mental retardation. Multiple organ system anomalies can occur. We report a male neonate with a linear-shaped nevus sebaceous over the face and scalp, whose prenatal brain sonogram revealed dilatation of the left lateral ventricle and a cysticlike lesion over the posterior cranial fossa. Postnatal magnetic resonance imaging of the brain showed hemimegalencephaly ipsilateral to the nevus sebaceous. Despite no seizures occurring during hospitalization, the diagnosis was established according to typical cutaneous lesions and brain images.