Uteroplacental insufficiency is a major cause of perinatal mortality and postnatal morbidity. Doppler velocimetry has been used to assess well-being of the fetus for several years. In the present study we evaluated the perinatal outcome of growth retarded fetuses with presence or absence of diastolic flow in umbilical artery at Doppler analysis. Forty-six pregnant women with intra-uterine-growth-retardation were studied. Ultrasound assessment of amniotic fluid was performed on alternate days until parturition. A weekly ultrasound measurement of fetal abdominal circumference was done. Doppler analysis of fetal/maternal circulation was performed upon arrival of the patient in hospital and thereafter on alternate days until delivery. Fetal blood was sampled by cordocentesis for immediate blood-gas analysis. In the group (n = 26) with absent or reversed diastolic flow in the umbilical artery, we observed a correspondingly worse blood-gas analysis; a reduced time interposed between the diagnosis and the delivery; a reduced birth weight associated with an increased fetal risk and with a perinatal mortality approaching 60%. Our data suggest that absent or reversed diastolic flow in umbilical artery of growth-retarded fetuses, associated with alterations in other vessels, are ominous signs of serious fetal compromise.