This study deals with the person-to-person variation in the levels of lead and cadmium in the blood of 6437 subjects (2883 men and 3554 women). The lead level (Pb-B) is clearly higher in men than in women, and the cadmium level (Cd-B) is a little higher in men than in women. Only the Pb-B varies according to age for both sexes. The results reveal that the consumption of alcohol could play an important part in the variation of lead and cadmium levels in the blood; the consumption of alcohol is associated with an increase in Pb-B but a decrease in Cd-B. These variations involving alcohol consumption remain significant regardless of smoking habits. On the other hand, an increase in Pb-B and Cd-B has been noted among smokers and, to a lesser degree, among former smokers, compared with non-smokers.