The molecular clock orchestrates the circadian integration and organization of many aspects of physiology that correspond with the duration of the rotation of the earth on its axis, ie, 24 hours. Circadian rhythms influence nearly every important physiologic process. The human cardiovascular system and cardiovascular disease are influenced by circadian rhythms. It is now evident that molecular circadian clocks play a role in the regulation of daily oscillations in cardiovascular function. The morning excess and evening reduction in the frequency of atherothrombotic cardiovascular events may be derived in part from the circadian variation in fibrinolytic activity. Here, we review the circadian regulation of cardiovascular function and its role in cardiovascular events...