Experiments were carried out to investigate the effect of garlic, both fresh and old, on hypercholesterolemia. Forty healthy rabbits were equally divided into four groups, namely control, cholesterol, fresh garlic and old garlic. Except the control group, each rabbit in the other three groups was given 0.5g of cholesterol every day. The rabbits of fresh and old garlic groups were fed in addition respectively with fresh garlic, and garlic that had been stored for seven months, the doses being 2g for each. The results showed that fresh garlic had a significant effect of reducing diet-induced hypercholesterolemia and diminishing arteriosclerotic changes in aorta, but old garlic failed to show such effects.During the 50-day period when rabbits were fed with fresh or old garlic no toxic reaction was observed.