OBJECTIVE To assess longitudinally fetal cerebral vasodilatation in small-for-gestational age fetuses to investigate whether intrauterine death might be predictable. METHODS Prospective observational study. METHODS Ultrasound department in a university hospital. METHODS Five pregnancies with ultrasonographically confirmed small fetuses (abdominal circumference less than the 3rd centile) monitored longitudinally until time of intrauterine death. METHODS Time between last ultrasound examination and diagnosis of intrauterine death, and variation in middle cerebral artery pulsitility index prior to death. RESULTS Two of the five fetuses showed a reversal of adaptation (as indicated by an elevation of the middle cerebral artery pulsitility index) within 48 hours of intrauterine death. The other three had their final ultrasound examination 3 to 7 days before death and showed no such reversal of adaptation. CONCLUSIONS Reversal of adaptation in fetal hypoxaemia as indicated by a rise in the middle cerebral artery pulsitility index may be a predictor of intrauterine death within 48 hours. Whether delivery after reversal of adaptation would result in salvage of neurologically intact babies needs to be investigated.