It has been known that garlic, one of the essential ingredients of spices in Korean food, has a hypotensive effect. The following experiments were done to compare the effect of heat treatment of garlic on change in blood pressure. We selected SHR(Spontaneously Hypertension Rat) for experimental animals since, in the case of human beings, 85~90% of high blood pressure is in hereditary origin. Animals were divided into 3 groups, control group(no garlic), 3% raw garlic group and 3% heated garlic group. Serum was analyzed for lipid concentration, and plasma for prothrombin time and fi-brinogen concentration. The effects of heat treatment of garlic were as follow. There was no significant differences in body weight gain and feed efficiency ratio except that feed intake of 3% heated garlic-fed group was significantly lower than that of control group and 3% raw garlic-fed group. Garlic-fed groups, in contrast to the control group, showed significant difference in cholesterol content in pro-thrombin time and in fibrinogen concentration. Taken together, hypotensive effects of garlic on high blood pressure were significant. Regardless of heat treatment both heated garlic and raw garlic showed hypotensive effects.