The transplantation of a heart restores the quality of life and productivity to patients who have experienced severe loss of contractility of heart muscle during an infection or as a result of long-lasting chronic heart disease. Monitoring for allograft rejection requires expensive procedures whereby, with catheterisation of the right heart, endomyocardial biopsies are retrieved. Evaluation by the pathologist uses a standardised diagnostic scheme which is in use worldwide. We have tested the interobserver agreement in a very heterogeneous group of examining pathologists and found moderate agreement with a kappa value of 0.52. The development of other methods to improve and even to replace invasive procedures for monitoring acceptance/rejection of a cardiac allograft requires interdisciplinary cooperation.