We analyzed the spectrum of neural-tube defects associated with maternal exposure to antiepileptic drugs (AEDs) and the possible contribution of familial and genetic factors to epilepsy or neural-tube defects. No specific association with maternal family history of neural-tube defects or epilepsy was seen. The ratio of spina bifida to anencephaly (33:1) suggested a specific association with caudal defects. Hydrocephaly was documented in at least 21 cases. Other midline defects, all associated with valproate (VPA), were hypospadias (two), hypertelorism (two), partial agenesis of corpus callosum, agenesis of septum pellucidum with lissencephaly of medial sides of occipital lobes, Dandy-Walker anomaly, and ventricular septal defect. This study shows that most neural-tube defects following maternal VPA use are severe open defects. They are frequently complicated by hydrocephaly and other midline defects. Prenatal diagnosis is possible.