Aims: To evaluate the impact of cigarette smoking on the sleep quality of patients with masticatory myofascial pain and to determine whether the association between smoking and impaired sleep is influenced by other factors such as demographic, psychological, and behavioral variables. Methods: Data from a retrospective case series of 529 patients diagnosed with masticatory myofascial pain according to group I of the Research Diagnostic Criteria for Temporomandibular Disorders were obtained. Patients completed a standardized pain questionnaire and psychometric tests. Differences between smokers and nonsmokers were evaluated using independent samples t tests and chi-square tests. Hierarchical linear multiple regression models were used to examine predictors of sleep disturbances. Results: Of the entire sample, 170 (32%) reported that they were smokers. Smokers reported higher pain severity and more sleep disturbances and psychological distress than nonsmokers. Cigarette smoking significantly predicted sleep disturbance (β = 0.229, P .001), but this relationship was attenuated after controlling for pain severity and psychological distress (β = 0.122, P .001). Conclusion: Cigarette smoking is associated with numerous adverse health outcomes, including pain severity, alterations in mood, and disrupted sleep, and seems to be a significant predictor of sleep quality in patients with masticatory myofascial pain. Keywords: masticatory myofascial pain, psychological distress, sleep quality, smoking, temporomandibular disorders