Gluconeogenic and oxidative capabilities with lactate as a substrate were studied in perfused livers isolated from rats in late sepsis. Glucose release in the presence of 5 mM lactate was significantly depressed in livers from septic rats. When gluconeogenesis was stimulated by phenylephrine, livers from septic rats exhibited both a decreased sensitivity and lower maximal rate of glucose release when compared with livers from sham-operated rats. Oxygen consumption (VO 2 ) by perfused livers from septic rats was also depressed under the above conditions. The addition of lysine in concentrtions greater than 0.5 mM restored glucose production in livers from septic rats to a rate not different from sham-operated controls but did not restore VO 2 . However, inclusion of lysine (5 mM) in the perfusate was not able to restore sensitivity to stimulation by phenylephrine in livers from septic rats. Although hepatic ATP levels were depressed in sepsis, the decrease was not sufficient to explain the decreased rates of glucose production. We conclude from these results that primary cellular defects in gluconeogenic and oxidative capabilities occur during sepsis that are independent of inadequate perfusion.