Supragingival calculus is frequent in all ages from adolescence to old age. The influence of tobacco smoking on the occurrence and severity of supragingival calculus has received surprisingly little attention. The present investigation conducted in a population of 258 dentally aware individuals in the age range 20-69 years, was initiated to elucidate the relationship between tobacco smoking and supragingival calculus, taking into account possible confounding factors such as age, gender, oral hygiene and gingival inflammation. The calculus deposition was bilaterally assessed on the lingual surfaces of the mandibular anteriors and the vestibular surfaces of the maxillary premolars and molars. The overall prevalence of supragingival calculus was 69% ranging from 59% in age group 20-34 years to 84% in age group 50-69 years. The prevalence rates for current smokers, former smokers, and nonsmokers were 86%, 66%, and 65%. The differences between smoking groups were statistically significant (p<0.05). The influence of smoking was independent of age, plaque and gingival inflammation. In former smokers who had stopped smoking in the distant past, the occurrence and severity of supragingival calculus were very close to those in individuals who had never smoked, suggesting that the effect of smoking is reversible. The observations indicate a strong and independent association between tobacco smoking and supragingival calculus deposition. The avoidance of excess deposition of supragingival calculus, therefore, is a further argument for reducing smoking in the population.