The purpose of this study was to investigate the effect of dietary taurine supplementation on plasma and liver lipid concentrations, and free amino acid concentrations in rats fed a high-cholesterol diet. Twenty male rats (body weight 151 +/- 1.9 g) were randomly divided into two groups. The rats in the control group were fed on 1.5% cholesterol diet (control) and those in the experimental group were fed with 1.5% cholesterol and 1.5% taurine diet (TSD). All rats were fed with the experimental diets and deionized water ad libitum for 5 weeks. The plasma glucose and lipid concentrations were measured using commercial kits with enzymatic methods and liver lipid concentrations with the Folch method. The concentrations of free amino acids in plasma were determined with an automated amino acid analyzer based on ion-exchange chromatography. There were no significant differences in the body weight gain, food intake and food efficiency ratio between the control and experimental groups. The rats fed TSD had significantly lower liver weight and liver weight/body weight ratio than those fed control diet. The plasma concentrations of total cholesterol, glucose and LDL-cholesterol were significantly reduced in the rats fed TSD compared to those fed control diet. The rats fed TSD showed significantly decreased liver levels of cholesterol and triglyceride. The HDL-cholesterol level was higher in the rats fed TSD than those fed control diet. The plasma taurine concentrations were not significantly different between two groups. They exhibited significant negative correlation with the plasma total cholesterol and liver triglyceride concentrations. These results suggest the possible role of taurine as a hypocholesterolemic agent in the rats fed a high cholesterol diet. Taurine supplementation did not cause any characteristic changes in the plasma aminogram pattern, body weight gain, and food intake.