The effects of fetal nutritional supplementation on experimentally induced growth retardation were investigated in third-trimester sheep. The control group, C, was fed ad libitum (n = 8). Group R received a protein- and calorie-restricted diet over the last 3 weeks of gestation (n = 8). Group RS was given the same restricted diet as group R, and fetal, intragastric supplements of amino acids and glucose (n = 7). Over the experimental period, maternal weight increased 4.1 ± 0.6 kg in C but was stable in R and RS (p < 0.01). R and RS ewes and fetuses showed biochemical evidence of malnutrition but the changes were less severe in the RS group (p < 0.05). Nutrient levels did not change in group C ewes and fetuses. At delivery, R lambs were smaller in weight and length than RS or C (p < 0.05); gestational ages were the same. Weights were: R, 2,702 ± 182 g; RS, 3,235 ± 121 g; and C, 3,290 ± 297 g. R also had lower fetal to maternal weight ratios and higher brain to body weight ratios than RS or C (p ≤ 0.05). Placental size was reduced 28% in R compared to C (p < 0.05) and was intermediate in RS. The disparity in fetal size was explained by differences in nutrient acquisition between groups. Over the experimental period, caloric intake rose 24% in C fetuses; near delivery, they had the highest umbilical uptakes of carbohydrate and α-amino nitrogen. After maternal diet was limited, R and RS fetuses had dramatic decreases in umbilical uptake of α-amino nitrogen and static umbilical uptakes of carbohydrate. Caloric intake fell 42% in R. RS fetuses, however, were receiving sufficient gastric supplementation so that umbilical + gastrointestinal carbohydrate uptake equalled that of controls, and entry of α-amino nitrogen and calories was intermediate, between those of R and C. Fetal oxygen consumption reflected the differences in nutrient uptake, being greatest in C, lowest in R and intermediate in RS. Fetal supplementation lessened the drain on maternal nutrients and promoted more normal fetal growth and metabolism.