Objective. This study tested the hypothesis that a heart maintained in arrest by retrograde cardioplegia (RC) can recover metabolic and contractile function to a level comparable to that of antegrade cardioplegia (AC). Methods. Isolated Langendorff piglet hearts were subjected a protocol consisting of 30 minutes of control perfusion, 45 minutes of arrest, and 30 minutes of reperfusion. During the control and reperfusion periods, the hearts were pelfused using Krebs-Henseleit (K-H) solution. Cardioplegic arrest was induced with two minutes of AC. Arrest was maintained for 43 minutes with continuous RC in group 1. The hearts in roup 2 were subjected to 45 minutes of continuous AC. Myocardial energy metabolism and contractile function in the two groups were compared by assessing energy metabolites using $\sp{31}$P MR spectroscopy and determining myocardial O$\sb2$ consumption (MVO$\sb2)$ and measuring intraventricular pressure. (Abstract shortened by UMI.)