Fetal hepatic insulin binding was studied in term fetal rats born to control mothers, mothers fasted for 48 h and mothers made hyperinsulinemic by the chronic, exogenous administration of insulin for 5 days prior to term. Maternal hyperinsulinemia was associated with fetal hypoglycemia and an approx. 70% reduction in fetal plasma insulin. Fetuses from these mothers exhibited an increase in hepatic insulin binding as indicated by a significant change in Scatchard analyses. No significant effect on fetal hepatic insulin binding by Scatchard analysis was seen with maternal fasting, despite a modest decrease in fetal plasma insulin. However, analysis of all animals showed that high-affinity fetal hepatic insulin binding and specific 125I-insulin binding were inversely correlated with fetal plasma insulin concentration. These results indicate that fetal rat liver, similar to adult rat liver, responds to a decrease in circulating insulin to below normal concentrations with an increase in insulin receptor binding.