Introduction: The aim of this study was to investigate the relationship between smoking and the prevalence of apical periodontitis and root canal treatment in hypertensive patients. Methods: In a cross-sectional study, the records of 100 hypertensive patients, 50 smokers and 50 nonsmokers, were examined. Periapical status of all teeth was assessed by using the periapical index score. Results: Apical periodontitis in 1 or more teeth was found in 92% of smoker patients and in 44% of nonsmoker subjects (P =.000; odds ratio [OR], 16.8; 95% confidence interval [CI], 4.6–61.3). One or more root-filled teeth were found in 58% and 20% of smoker and nonsmoker subjects, respectively (P <.01; OR, 5.5; 95% CI, 2.3–13.5). Among smoker hypertensive patients, 6% of the teeth had apical periodontitis, whereas in the nonsmoker subjects, 2% of teeth were affected (P <.01; OR, 3.3; 95% CI, 2.0–5.4). The percentage of root-filled teeth in the smoker and nonsmoker groups was 3.6% and 1.2%, respectively (P <.01; OR, 2.9; 95% CI, 1.6–5.5). Conclusions: The prevalence of apical periodontitis and root canal treatment was significantly higher in smoker hypertensive patients compared with nonsmoker subjects.