We report a case of complete bilateral cerebellar infarction diagnosed in utero by routine prenatal ultrasound and magnetic resonance imaging in a 26-week-old fetus. This posterior fossa ischemic stroke with secondary hemorrhage caused transient obstructive hydrocephalus and likely occurred subsequent to vertebrobasilar artery thrombosis. Such posterior fossa ischemic insults diagnosed in utero are rare with scarce clinical reports. The serial imaging characteristics, clinical, and developmental implications of this case are reviewed.