Phytosterols are natural dietary components and their lowering effect on serum cholesterol level has been well documented. There have been few reports about the effect of less than 1g/day of phytosterol on serum cholesterol level. We attempted to investigate serum cholesterol lowering effect of phytosterol at 2 relatively low doses. In a randomized, double-blind, 3-group parallel protocol, 67 healthy men with a total cholesterol of 221.5 ± 17.0 (mean ± SD, mg/dL) consumed each about 0.04 g/day, 0.29 g/day and 0.45 g/day of phytosterol (as the major free sterol) for 4 weeks. The level of total cholesterol decreased by 1.0%, 0.5% and 7.9% in the control, the low-and the high-phytosterol group, respectively. As for LDL-cholesterol level, these decreases were 1.8%, 1.0% and 9.5%, respectively. The relative reduction rates of total-and LDL-cholesterol levels in the high-phytosterol group were significantly different from the others, whereas no difference between the control and the low-phytosterol group were observed. No significant difference in the levels of VLDL-cholesterol, HDL-cholesterol or triacylglycerol were found among the groups. Apolipoprotein B and RLP-cholesterol levels were also lower in the higher group. These results indicate that a daily intake of about 0.45 g phytosterol beneficially affect the levels of total- and LDL-cholesterol even in healthy subjects with a slightly elevated serum cholesterol level, and that it may be helpful in reducing the risk of CHD.