During several decades of this century, the classical physiological studies on the cardiovascular system have greatly improved our knowledge on the function of this system under normal and pathological conditions. This knowledge was the basis of the breakthrough for diagnostic techniques like the Swan-Ganz catheter, coronary arteriography, left and right heart biopsies, and invasive measurements of contractility, as well as therapeutic tools including aortocoronary bypass surgery, percutanous transluminal coronary angioplasty, and a broad field of pharmacological interventions for the whole spectrum of cardiovascular diseases, especially chronic heart failure. It was during the last decade that the scientific world focused on the evolution of molecular biology of the cardiovascular system so that cardiovascular physiology seemed to become less important. Regarding the myocardium, molecular alterations of important functional proteins (phenotype changes), as well as signal transduction pathways of contractility and cardiac growth have been elucidated. The functional importance of a number of genes has undoubtedly been proven with the help of transgenic animals. Mechanics and Energetics of the Myocardium provides an overview for those researchers and practioners interested in the broad field of molecular biology and physiology of the cardiovascular system.