Myocardial oxygen consumption (MyO<sub>2</sub>) was measured in intact, anesthetized dogs prior to and during an acute elevation of arterial free fatty acids (FFA). FFA were elevated by the infusion of a lipid emulsion (‘Intralipid’) coupled with heparin to intensify lipolysis. Intralipid infusion prior to heparin (n = 7) caused a small increase in FFA (352 ± 41–666 ± 67 µEq/l) without significant change in either MyO<sub>2</sub> or hemodynamics. Following heparin, arterial FFA rose from a base line, preheparin level of 649 ± 50–1,925 ± 186 µEq/l at 10 min, 1,988 ± 247 µ Eq/l at 20 min, and 1,750 ± 221 µ./Eq/l at 30 min. Hemodynamics were essentially stable throughout the study. No significant change was observed in either MyO<sub>2</sub> or mean coronary blood flow, while myocardial oxygen extraction showed a small but significant increase at 10 and 30 min. An acute elevation of arterial FFA within the physiologic range does not significantly affect myocardial oxygen consumption in the intact, closed-chest anesthetized dog.