A greater understanding of the role of biologic rhythms in cardiovascular functioning has recently been established. Circadian variations in ischemic events such as acute myocardial infarction, sudden cardiac death, and cerebrovascular emboli have been well documented. New approaches to therapy based on circadian fluctuations in physiology and pathology have led to better timing of drug administration and treatments to optimize desired outcomes and minimize untoward effects. This article discusses these emerging trends and gives examples related to beta-adrenergic blockade, nitrate and steroid therapy, and anticoagulation. Directions for future nursing research are suggested.