The authors report a case of minimal prenatal trauma producing a large subdural hematoma in the fetus, which was diagnosed in utero by MR imaging. The occurrence of such a complication is extremely rare in the absence of significant maternal trauma. Prenatally diagnosed intracranial hemorrhages, particularly those that are subdural in origin, have a poor prognosis in most cases. After birth, brain compression required a complex neurosurgical intervention because simple hematoma evacuation was not possible. The clinical and neurological outcome at 6 months was excellent, as confirmed by the neuroimaging findings.