AbstractGroups of fasted female rats were tube fed ethanol (6 g/kg b.w.), an isocaloric amount of glucose, or nothing. Half of the rats in each group were given hourly s.c. injections of nicotinic acid. 6 hrs after the feeding, 9–10‐H3oleic acid complexed to serum albumin was injected intravenously. 5 min later the rats were killed and concentrations of plasma free fatty acids and of liver glycerides and labeling of liver and carcass lipids was determined.Plasma free fatty acid concentrations were similar in the ethanol fed and the fasted rats but lower in the glucose fed rats. In all groups nicotinic acid lowered plasma free fatty acid concentration.Liver glyceride concentration was elevated in the ethanol fed rats. In all groups nicotinic acid lowered the liver glyceride concentration.Total liver radioactivity was highest in the ethanol fed rats, intermediary in the glucose fed rats and lowest in the fasted rats. The liver radioactivity was not significantly changed by nicotinic acid. It is suggested that the differences in liver radioactivity between the groups reflects differences in the oxidation of plasma free fatty acids taken up by the liver and that a major cause of the ethanol induced fatty liver is a decreased hepatic oxidation of plasma free fatty acids taken up at a normal r