OBJECTIVE To investigate blood-flow patterns in ductus venosus in growth-retarded fetuses. METHODS Reference ranges of ductus venosus flow velocities were constructed from a cross-sectional study of 179 normal fetuses between 16 to 38 weeks' gestation. and the ductus venosus flow-velocity waveforms in 11 small-for-gestational-age (SGA) fetuses were compared with normal patterns. RESULTS Of 179 pregnant women who were possible subjects, 175 were employed for the analysis, and ductus venosus flow-velocity waveforms were obtained in 197 out of 211 examinations (success rate = 93.4%). The peak forward velocities during (a) ventricular systoles, (b) the lowest forward velocities during atrial contractions, and (c) the time-averaged velocities all linearly increased as gestational ages increased [respectively: (a) slope, 1.135; constant, 31.720; (b) slope, 1.154; constant, 1.557; (c) slope, 1.240; constant, 19.386]. Peak forward velocities during ventricular systoles and time-averaged velocities in the SGA group did not differ from those of the normal group. Three SGA fetuses with abnormal flow in the umbilical artery showed a marked reduction of the lowest velocities during atrial contractions in the ductus venosus, and two of them showed no forward velocity at all. CONCLUSIONS The Doppler-velocity waveforms of ductus venosus showed a marked reduction of the end diastolic flow, especially in SGA fetuses with abnormal umbilical artery flows.