Abstract The effect of endotoxin upon oxygen consumption in a peripheral vascular bed was assessed in a canine hind-limb preparation. The left iliac vessels in 12 adult male mongrel dogs were isolated, the artery cannulated proximally and distally such that arterial inflow could be routed through a roller pump, and a nonocclusive sampling catheter placed in the vein. Oxygen consumption was then calculated as the product of flow rate and arteriovenous oxygen content difference at a series of flow rates before and after the systemic administration of endotoxin (3 mg/kg) or saline solution. At each flow rate, oxygen consumption by the extremities of endotoxic animals was significantly greater (P < 0.01) than that measured in control animals. This finding mitigates the hypothesis that endotoxin has a direct effect on cells reducing tissue oxygen consumption.