69 singleton pregnancies, with a diagnosis of intra-uterine growth retardation (IUGR) at ultrasound, were followed until delivery by pulsed Doppler evaluations in fetal thoracic descending aorta (DA) and umbilical artery (UA). Three haemodynamic groups were described according to flow characteristics expressed as the pulsatility index (PI) of the vessel under study. In each group the relative incidence of fetal distress, diagnosed according to CTG monitoring, was evaluated. Fetal distress occurred in 75% of the cases with a raised PI both in DA and UA, in 40% of the cases with a raised PI only in DA and in 21% of the cases with 'normal' PI values in both vessels. It can be said that Doppler flow measurements can be useful in defining the actual haemodynamic situation of the fetus with possible clarifications concerning its 'stressed' or 'distressed' condition and residual capacities to substain hypoxia.