Cigarette smoking produces lipo-apoprotein modifications, which makes it more atherogenic. In this study we have evaluated lipids and apoproteins in 178 normolipidemic, healthy subjects, in relation to their smoking habits. In smokers we have found lower levels of HDL-cholesterol and apo A-I and higher levels of triglyceride and apo B. Number of cigarette smoked in a day directly correlated with triglycerides and apo B (r = 0.321 and 0.313 respectively) and inversely with HDL-cholesterol (r = -0.274). These alterations seem to be due to an inhibition that smoking could cause on lipolytic processes. Further studies need to establish influences that smoking-related alterations have in the atherosclerotic lesions of smokers.