BACKGROUND: The extent to which differences in cardiovascular risk between smokers with similar daily tobacco consumption may be related to plasma levels of inflammation-sensitive proteins (ISP) and whether these proteins are associated with levels of carboxyhemoglobin (COHb%) have not been clarified. METHODS AND RESULTS: In a population-based cohort of 1489 never smokers, 1685 former smokers, and 2901 current smokers, aged 28 to 61 years, plasma levels of orosomucoid (alpha(1)-acid glycoprotein), alpha(1)-antitrypsin, haptoglobin, fibrinogen, and ceruloplasmin were measured. COHb% levels were available for 2098 of them. Incidence of myocardial infarction, stroke, and death were monitored over 18.7+/-4.7 years. The proportion with high ISP levels (ie, > or =2 ISP in the top quartile) increased progressively with daily tobacco consumption (P