The effects of maternal intake and gestational age on materno-fetal transport of vitamin C were investigated in female Dunkin-Hartley guinea-pigs. Twenty-four time-mated dams were fed on either a moderate-vitamin C (group A) or a high-vitamin C (group B) diet, throughout pregnancy. At days 49, 63 and 66 of gestation, and at term, three animals from each group were killed and fetuses removed by hysterectomy. Plasma, liver, kidney, lungs, heart, placenta and amniotic fluid were collected from dams and fetuses and subsequently analysed for vitamin C. Fetal plasma and amniotic fluid concentrations showed negative associations with gestational age for both dietary groups, independent of an effect of dam (P < 0.001). A similar, though not significant, effect of gestational age was observed on placental vitamin C and group A fetal tissue concentrations. Fetal plasma, placental and amniotic fluid vitamin C concentrations were significantly higher in group B than group A (P < 0.001), suggesting the influence of maternal diet. Although the level of maternal vitamin C intake can influence the circulating concentration in the fetus, there is a decrease associated with increasing gestational age, independent of the maternal diet. The gestational age-dependent change in the fetal accumulation of vitamin C may reflect changes in the rate of placental transfer.