Background: Adhesion of leukocytes to myocardium or vascular endothelium has been known as an importation initial step in the ischemia-reperfusion injury which may affect the cardiac function. Therefore, leukocyte-depleted reperfusion may inhibit ischemia-reperfusion induced functional and ultrastructural deterioration. In this study, we quantified the time-dependent expression of the vascular cell adhesion molecule-1(VCMA-1) on piglet myocardium and demonstrated its relation to functional recovery using isolated piglet heart perfusion model. Material and Method: Neonatal(1 to 3 day old) piglet heart was harvested with 4$^{circ}C$ University of Wisconsin solution (UWS) and presrved in the same solution for 12 hours. Ex vivo model of an isolated working neonatal piglet heart perfusion consisting of membrane oxygenator and roller-pump was used (Fig. 1). Hearts were grouped into leukocyte-non-depleted (group A, n=8) and leukocyte-depleted group(group B, n=8). In group B, hearts were reperfused with leukocyte-depleted blood using a leukocyte filter (Sepacell R, Asahi Medical, Japan). Segments of right atrium were taken before and after 1, 2, 3, and 4 hours of reperfusion for the evaluation of expression of VCAM-1. The intensity of immunohistochyemical satining of the VCAM-1 on the myocardium were graded semiquantitatively (0 to 4). For the evaluation of myocardial stroke work indices were calculated as well at the same time-points. Result: Mean expressins of VCAM-1 on the myocardium at 0, 1, 2, 3, adn 4 hours of reperfusion were 0.63, 1.44, 1.64, 2.65, and 3.34 in group A, while 0.56, 1.40, 1.50, 1.88 and 2.14 in group B (Fig. 3). Mean stroke work indices at 0.5, 1, 2, 3, and 4 hours after reperfusion were 1.35$ imes$104, 1.32$ imes$104, 1.14$ imes$104, 0.81$ imes$104, 0.68$ imes$104 erg/gm in group A, while 1.40$ imes$104, 1.43$ imes$104, 1.43$ imes$104, 1.28$ imes$104, and 1.12$ imes$104 erg/em in group B(Fig. 4). Conclusion : In this study, we demonstrated that leukocyte-depletion attenuated the expression of VCAM-1 during reperfusion and the time-dependent functional deterioration of the myocardium was well correlated with the degree of VCAM-1 expression.