Preconditioning is a phenomenon, where brief periods of stress such as ischemia, heat shock or certain pharmacological agents make the heart tolerant to subsequent lethal ischemic injury. Preconditioning seems to involve a variety of stress signals which include activation of membrane receptors and signaling molecules such as protein kinase C, mitogen-activated protein kinases, opening of ATP-sensitive potassium channel and expression of a number of protective proteins. In this review, the potential role of these mechanisms is discussed.