Studies that have examined the effect of age on the myocardium do not support the notion that a generalized decline in myocardial function occurs with adult aging but, rather, that certain specific changes in cardiac biochemistry and function occur. Although in many instances the molecular bases for these changes have not been precisely defined, sufficient clues regarding their nature are at hand to provide at least the first step toward an understanding of the dramatic effects of aging or time on the myocardium. A fundamental understanding of the effects of aging will provide an additional dimension to studies of myocardial biochemistry and function and may be useful in elucidating mechanisms of excitation-contraction coupling in the heart.