In two representative population surveys (n1 = 1712, n2 = 3757, age-range: 25-64 years) from six towns in Northern Badenia (FRG) self-reported smoking habits and blood thiocyanate levels were compared. In Survey 1 the smoking prevalence was 44.1% in males and 32.9% in females, in Survey 2 45.0% in males and 26.5% in females. In agreement with previous studies it was proved that thiocyanate measurements allow to distinguish groups of non-smokers from smokers, whilst not being specific enough to reflect precisely the quantity of tobacco consumption of the individual. A quadratic regression of thiocyanate levels on cigarette consumption provided a better fit and a higher correlation coefficient than linear regression, indicating a saturation effect, i.e., there is no further increase of thiocyanate levels when more than about 30 cigarettes daily are consumed.