The impact of cold storage of cardiac allografts on expression of major histocompatibility complex antigens and vascular adhesion molecules is not known. We obtained serial endomyocardial biopsy specimens at harvest, on implantation, and approximately 15 minutes after reperfusion from six consecutive human cardiac allografts stored in University of Wisconsin solution. Cold ischemia time was 187 +/- 45 minutes. A fourth endomyocardial biopsy specimen was obtained from the recipients of cardiac allografts 1 week after operation. Expression of major histocompatibility complex antigens and vascular adhesion molecules was studied by immunohistochemistry. The intensity was scored blindly by a semiquantitative method. On vascular endothelial cells, the expression of major histocompatibility complex class I and II antigens was strong; ICAM-1 expression was moderate, and expression of VCAM-1 and ELAM-1 was weak to absent. The expression of these antigens on vascular endothelial cells did not change in sequential biopsy specimens. The expression of major histocompatibility complex class I antigens on myocardial cells was weak and remained unchanged. Myocardial cells did not express major histocompatibility complex class II antigens, ICAM-1, VCAM-1, or ELAM-1 on serial examinations. During cold storage of cardiac allografts in University of Wisconsin solution, the expression of major histocompatibility complex antigens and vascular adhesion molecules on endothelial cells and myocardial cells remains unchanged.