The effect of clofibrate on the same subjects in similar test conditions were used as a control to verify the alleged beneficial effects from garlic and onion on alimentary hyperlipemia in normals and in cases with ischemic heart disease. The results showed that clofibrate checked the fat-induced (a) rises of serum triglyceride and plasma fibrinogen, and (b) falls of coagulation time (CT) and blood fibrinolytic activity (BFA). Only garlic had a clofibrate-like effect on CT but both garlic and onion checked the postprandial fall of BFA. Clofibrate, however, increased BFA even above the fasting level. Serum cholesterol and beta-lipoprotein were not appreciably affected by fat with or without any drug. Thus, surprisingly, the so-called beneficial effects of garlic and onion were not seen in subjects who had shown significant changes after clofibrate.