Saturated fatty acids and cholesterol in the diet raise the plasma cholesterol concentration, and a reduction in these constituents is recommended widely. However, there is not general agreement as to which nutrients should replace saturated fatty acids. Several different substitute nutrients are possible. In this study, three cholesterol-lowering diets were compared in nine men living in a domiciliary. On a typical American diet at baseline, cholesterol levels were in the normal range. One replacement diet was high in polyunsaturated fatty acids (High Poly); another had 30% fat and corresponded to the American Heart Association's (AHA) recommended diet for the general public (AHA phase I); the third diet had 20% fat, equivalent to the AHA phase III diet for treatment of hypercholesterolemia. Compared with baseline levels, all diets caused similar reductions in total cholesterol and low-density lipoprotein cholesterol levels, but the High Poly and AHA phase III diets lowered the high-density lipoprotein cholesterol level more than the AHA phase I diet. Thus, for the limited number of patients in this study, the diet recommended for the general public appeared as effective for lowering of cholesterol levels as diets containing more polyunsaturates or more carbohydrates.