Conflicting patterns of myocardial cell adhesion molecule expression associated with cardiac rejection have emerged from numerous studies of randomly selected cardiac biopsies. We designed a prospective, longitudinal study which reports both qualitative and quantitative levels of myocardial ICAM-1, VCAM-1, E-selectin, and P-selectin expression in sequential human cardiac allograft biopsies. Intense ICAM-1 and VCAM-1 staining was found in all biopsies during the first three weeks after transplant and coincided with elevated serum levels of troponin T, a sensitive marker of ischemic myocyte injury. Baseline ICAM-1 and VCAM-1 expression returned within three to four weeks, as did serum troponin T levels in all patients who did not develop rejection. All 29 rejection episodes encountered were associated with intense ICAM-1 staining, while 24 of the 29 (83%) had intense VCAM-1 staining. Increased ELAM-1 and CD62 staining was only rarely observed. Persistence of increased ICAM-1 and VCAM-1 staining after treated rejection episodes predicted a recurrent rejection episode within two months (75% positive and 100% negative predictive value). Objective quantitative measurements by radioimmunoassay (RIA) confirmed these patterns of induced ICAM-1 and VCAM-1 expression. Thus, longitudinal monitoring of serial biopsies for myocardial ICAM-1 and VCAM-1 expression could be useful in the early detection of rejection episodes and monitoring the efficacy of immunosuppressive therapy.