On the basis of a previous study in deceased parrots it was suggested that a high intake of alpha-linolenic acid might protect against the development of atherosclerosis. To test our suggestion, a feeding experiment was carried out with Japanese quail. Quails are known to develop atherosclerosis when cholesterol is added to the diet. During 80 days, four different diets were fed to groups of 17 or 18 quails. There was a control group that was fed a cholesterol-free diet and the three remaining groups were fed diets fortified with cholesterol. The experimental, cholesterol-rich diets were either rich in saturated fatty acids, linoleic or alpha-linolenic acid, the exchange of the fatty acids being the only variable. At the end of the experiment, blood was collected for determination of plasma lipids, the degree of atherosclerosis was scored and tissues were collected for fatty acid analyses. Addition of 2% cholesterol to the diet resulted in a two-fold increase of plasma cholesterol and a 10-fold increase in liver cholesterol. Cholesterol feeding induced plaque formation. No significant effect of alpha-linolenic acid versus either linoleic acid or saturated fatty acids (lauric plus myristic plus palmitic acid) was seen with regard to atherosclerosis and plasma cholesterol. The fatty acid composition of the diets was reflected in the tissue fatty acid composition, but there were significant differences between tissues. It is concluded that, under the conditions of this study, a differential effect on the development of atherosclerosis of alpha-linolenic acid, linoleic acid and saturated fatty acids could not be demonstrated.