Hormel miniature pigs were studied over a period of 24 weeks to observe the changes in serum lipoprotein pattern, cholesteryl ester, free cholesterol, and triglyceride in the atherogenic-fed pigs. These pigs were compared to age-related control animals in our breeding herd. Pigs fed the atherogenic diet (20% tallow, 3% cholesterol, and a bile supplement) exhibited a heterogeneous response but showed mean increases in cholesteryl ester (571 mg/dl) and free cholesterol (226 mg/dl), a slight increase in triglyceride (58 mg/dl), and a severe hyperbetalipoproteinemia. Three animals with the highest cholesteryl ester (all above 600 mg/dl) had resolvable beta components in their 1.006 g/ml very low density lipoprotein fraction (type III), as well as huge increases in the Sf 12-20 low density lipoprotein fraction. The other four animals had substantial increases in Sf 0-20, and the three highest had much of their low density lipoprotein in the Sf 12-20, or "remnant" fraction. The test pigs all showed gross lesions in the aorta with an increase in cholesteryl ester and free cholesterol in the tissue as compared with control animals.