The objective of this study was to examine the effects of seven dietary oils on the serum lipid patterns of rats. Seventy weanling Wistar Kyoto rats were divided into seven groups of ten rats each. Walnut oil (rich in PUFA), wheat germ oil (rich in PUFA), corn oil (rich in PUFA), canola oil (rich in monounsaturated fatty acids), fish oil (rich in PUFA), primrose oil (rich in PUFA), and palm oil (rich in saturated fatty acids) were employed for 21 days. Serum total cholesterol concentrations for rats fed palm oil, walnut oil, and wheat germ oil were significantly higher than were concentrations for rats receiving corn oil. fish oil, and primrose oil. The mean serum LDL cholesterol values for rats fed fish oil, primrose oil, and corn oil were significantly lower than those for rats fed walnut oil, wheat germ oil, canola oil, and palm oil. HDL cholesterol concentrations were the highest when wheat germ oil was fed and the lowest when fish oil was fed. The feeding of wheat germ oil and palm oil to rats resulted in considerably higher serum triglyceride levels than did all other treatments. The feeding of wheat germ oil to rats resulted in considerably higher serum phospholipid levels. Serum phospholipid concentrations were significantly lower in rats fed the canola oil, fish oil, ,and primrose oil diets, when compared to concentrations achieved with the feeding of walnut oil, wheat germ oil, corn oil, and palm oil. Palm oil, which has a high ratio of saturated to polyunsaturated fatty acids, resulted in the highest serum total cholesterol and highest LDL cholesterol levels, while fish oil, primrose oil, and corn oil produced the lowest total cholesterol and LDL cholesterol. Wheat germ oil produced the highest values for HDL cholesterol, triglycerides, and phospholipids. In general, feeding oils rich in polyunsaturated fatty acids produced more favorable responses than feeding oils containing large amounts of monounsaturated or saturated fatty acids.