The content and the distribution of the glycoconjugate sugar residues were investigated in the human umbilical cord from normally grown pregnancies and from pregnancies complicated by intra-uterine growth retardation with absent or reversed flow in the umbilical artery. The gestational age range was 29-41 weeks. For this purpose, a battery of eight horseradish peroxidase conjugated lectins was used (ConA, WGA, PNA, SBA, DBA, LTA, UEA I, and OOA; see text). Our data showed that in both study groups ConA, WGA and PNA (after neuraminidase digestion) and LTA, UEA I, and OOA reacted with Wharton's jelly and vessels of the umbilical cord from the first weeks of gestation considered. SBA reactivity was observed only in the amniotic epithelial cells of the jelly and in the endothelial cells of the vessels. The reactivity with the most part of the lectins decreased or was lacking in the various components of the umbilical cord between 39 and 41 weeks of gestation in the normal group and between 36 and 37 weeks of gestation in the pathological one. Moreover, the intensity of reactivity with ConA, WGA and PNA (after neuraminidase digestion) and LTA, UEA I, and OOA in the normal group and with PNA (before and after neuraminidase digestion) and LTA and OOA in the pathological one was stronger in the peripheral portion of the jelly with respect to the adventitial one. The reactivity with ConA and UEA I was stronger in the vein than in the arteries in both study groups. Some hypotheses are reported on the role played by the sugar residues in the normal and pathological umbilical cords.