Background: We reviewed recent progress in the study of the chronobiological aspects of the cardiovascular system. Methods: Medline was used as the main search tool, and the full texts of selected papers were obtained. Results: More than 300 references were found, and 52 of them, representing the major findings in this field, were included in the reference list. Results of these studies confirm that most cardiovascular physiological parameters (such as heart rate, blood pressure, electrocardiogram indices) and pathophysiological events (myocardial ischemia/infarction, sudden cardiac death) show circadian rhythms. Results also suggest that consideration of these rhythms is important for the diagnosis and treatment of cardiovascular disorders and that restoration of normal circadian rhythms may be associated with clinical improvement. Conclusion: The study of circadian rhythms in the cardiovascular system is emerging as an important area of investigation because of its potential implications for patient management.