Carnitine and its derivatives have recently been shown to protect cardiac metabolism and function in ischemic heart disease and other clinical conditions of myocardial ischemia. Potential mechanisms of this effect include an increase in glucose metabolism, a reduction of toxic effects of long-chain acyl-CoA and acyl-carnitine in myocytes, an increase in coronary blood flow and anti-arrhythmic effect. It has also been shown that propionyl-L-carnitine which penetrates faster than carnitine into myocytes is effective in inhibiting production of free radicals. Beneficial effects of carnitine supplementation have been demonstrated under a variety of clinical conditions such as acute cardiac ischemia, during extracorporeal circulation, in carnitine-dependent cardiomyopathy as well as in patients with chronic circulatory failure and in cardiogenic shock. However, further studies are required before carnitine administration could be recommended as a routine procedure in ischemic heart disease or before cardiopulmonary bypass.