Pregnant rats at 12 and 21 days of gestation and their virgin controls were injected intravenously with U-14C-glycerol and decapitated 1, 3, or 10 min later. The conversion of labelled glycerol to 14 C-glucose was augmented in the 21-day pregnant rats. The disappearance of the newly formed 14C-glucose from blood was faster in both 12- and 21-day pregnant rats than in their controls, being partially retained as liver 14C-glycogen. The greatest amount of radioactivity in all tissues appeared in the carcass hydrosoluble fraction. This amount was smaller in the pregnant rats. The reduced utilization of glycerol by extrahepatic tissues allowed the 21-day pregnant rats to dispose a greater amount of this substrate for gluconeogenesis.