Although various studies have noted fatty-acid-mediated regulation of adipocyte lipolysis, determining the isolated effect of a single fatty acid is more difficult. We examined the influence of dietary oleic acid on adipose cell lipolytic activity and the tissue fat content independently of the variation in other dietary fatty acids. We fed 48 rats with six diets designed so that the oleic acid content was not correlated with the content of any other fatty acid and studied the lipolytic activity and fatty acid content of the tissues. There were no differences in the weight of the animals after the diet. The muscle fat content and the epinephrine-stimulated lipolytic activity varied significantly according to the dietary levels of oleic acid and the tissues, showing a dose-dependent behavior of the dietary oleic acid concentration. The results of this study show that diets rich in oleic acid have a beneficial effect on the regulation of lipid metabolism and body weight homeostasis.