Results in animals and in man indicate that in many circumstances, lipemia is not closely related to the severity of atherosclerosis nor to the incidence of coronary heart disease (CHD) or the intake of saturated fats as observed in paired studies between farmers from Moselle and Var in France and from West and East Scotland. In rabbits, an increased response of platelets to thrombin occurs before any deposition of cholesterol, as a result of a saturated fat feeding. Under these conditions, the addition of alcohol to the drinking water decreases significantly both the platelet response to thrombin and the severity of atherosclerotic lesions without much affecting plasma cholesterol. In farmers from Moselle and Var (as well as from Scotland), platelet functions, namely the aggregation to thrombin and their clotting activity, i.e. PF3, are closely related to the intake of saturated fats, either as a result of the long-term feeding or of a 1 year change in the diet of Moselle farmers. Certain platelet functions appear to be the only blood parameter related to the incidence of CHD and significantly correlated on a group, as well as on an individual basis, with the intake of saturated fat, and inversely related with that of calcium. Saturated fats and calcium are known to be the two main dietary factors related to CHD. These results suggest that the intermediate link between dietary fats and CHD might be blood platelets rather than serum lipids, through an effect on both thrombosis and atherosclerosis.