To examine the cholesterolemic nature of long-chain saturated fatty acids in relation to the effect of palm oil, rats and hamsters were fed purified diets containing 7 to 8% interesterified fats in which saturated fatty acids, lauric, myristic, palmitic, and stearic acids were the sole variable. Feeding with a stearic acid fat-containing diet to these animals resulted in lower absorption of dietary fat, greater excretion of fecal neutral steroids, and lower concentration of hepatic cholesterol. The lower concentration of plasma cholesterol in hamsters fed a stearic acid fat-containing diet without cholesterol seemed to be attributed to the lower intestinal absorption of cholesterol rather than the enhanced catabolism of plasma cholesterol. Although not as markedly, palmitic acid also showed effects somewhat similar to those of stearic acid. Thus, saturated fatty acids exerted distinct effects on various parameters of lipid metabolism, and hence, the effect of palm oil should be evaluated at the broad view point.