Active smoking is a well known risk factor for the development of atherosclerosis and in particular coronary heart disease and peripheral vascular disease. The negative effects of active smoking demonstrated on platelet function, the eicosanoid system and platelet thromboxane A2 generation may contribute to the hemostatic imbalance reported. Recently, the problem of passive smoking as a health risk has been widely discussed. Detailed information on the role of passive smoking on hemostatic parameters, however, is still very limited. As far as present knowledge is concerned, platelet activation seems to be significantly involved in the deleterious vascular effects of passive smoking as well.