The relation between smoking and apical periodontitis has been little studied to date. The aim of the present study was to investigate whether tobacco smoking might be associated with the prevalence or severity of periapical lesions. A total of 247 individuals, 81 current smokers, 63 former smokers, and 103 non-smokers participated in the study. The periapical condition was expressed as the number and percentage of radiographically detectable lesions and, in addition, as a severity index. The overall prevalence of apical periodontitis was 52% and the overall prevalence of endodontic treatment 58%. There was no significant influence of smoking on the prevalence of either apical periodontitis or endodontic treatment. The mean number (percentage) of periapical lesions per person was 1.9 (6%) in current smokers, 1.5 (4%) in former smokers, and 1.0 (3%) in non-smokers. Controlling for age, the association between smoking and periapical lesions was not statistically significant. The mean periapical severity index including all teeth, or teeth affected by periapical lesions alone, did not significantly differ between smoking groups. It is concluded that the present observations do not lend support to the assumption that tobacco smoking is associated with apical periodontitis.