Objectives. Monounsaturated fatty acid (MUFA)-rich diets were once considered an alternative therapy to prevent coronary heart disease. However, MUFA-rich diets were found to increase liver total cholesterol levels in animal experiments. The purpose of this study was to examine whether the addition of dietary cholesterol alters the effects of monounsaturated fatty acid (MUFA)-rich diets on lipid metabolism. Methods. Diets containing 0%, 0.25%, 0.5%, 0.75%, and 1% (w/w) cholesterol were added to MUFArich meals and fed to rats for 21 days. The concentrations of plasma cholesterol, low-density lipoprotein-cholesterol (LDL-C), high-density lipoprotein-cholesterol (HDL-C), and triacylglycerol (TAG) were determined by enzymatic precipitation methods. The concentrations of hepatic cholesterol, TAG, and hepatic lipase (HL) were also determined. Results. Plasma total cholesterol and LDL-C concentrations increased but the concentrations of HDL-C decreased in rats which were fed either a 0.75% or a 1% cholesterol diet. The LDL-C/HDL-C ratio significantly increased from 0.58 to 1.91 as the dietary cholesterol level increased from 0% to 1%. The cholesterol-fed rats showed significant increases in hepatic cholesterol and TAG levels. The addition of 0.25% (w/w) cholesterol resulted in increased hepatic cholesterol (2.9 fold) and TAG (72%) levels compared with a cholesterol-free diet. There was, however, no significant difference in HL activity between cholesterol-fed rats and rats which were fed a cholesterol-free diet. Conclusions. Extra dietary cholesterol altered plasma and hepatic lipid concentrations in rats which were fed a MUFA-rich diet.