Abstract Following the incidental diagnosis of triventricular hydrocephalus in a fetus 34 weeks after the mothers last menstrual period, during an uneventful pregnancy, 1.5-T brain magnetic resonance (MR) was carried out. A subependymal hemorrhage, which had not been revealed by transabdominal ultrasound, was found; this finding was confirmed by neonatal brain ultrasound and MR. Fetal MR allowed identification of the hemorrhage as the cause of the hydro-cephalus and also established its time of occurrence. Unexplained hydrocephalus should be included among the indications for fetal MR.