Utilizations of exogenous fat emulsion (Intralipid) in control, early septic, and late septic rats were studied. After intravenous infusion of14C‐Intralipid, cumulative amounts of14CO2in the expired breath in the 6‐hr period were 42.8 ± 1.8, 35.0 ± 1.8, and 28.5 ± 1.6% of the injected dose, respectively, for the three groups. The amount and the maximum rate of CO2production correlated with the severity of sepsis. Significantly greater amounts of plasma triglyceride and free fatty acids were also observed in septic rats. The hyperlipemia associated with the observed decrease in plasma clearance of lipids may account for the decreased utilization of exogenous fat in septic rats.(Journal of Parenteral and Enteral Nutrition8:14–17, 1983)