The study deals with the comparison of morphological, histochemical and biochemical methods applied to the detection of myocardial infarction in 150 medico-legal autopsies performed at the Institute of Forensic Pathology in Copenhagen. The study also included an NBT (formazan) test of cardiac cross-sections, and light microscopy and fluorescence microscopy of acridine orange-stained specimens from four different sites of the cardiac musculature. Specimens of myocardium from the same four sites and pericardial fluid were analysed biochemically at the Institute of Legal Medicine in Granada. The K+/Na+ ratio was determined in the myocardial tissue and total creatine phosphokinase activity, creatine phosphokinase isoenzymes (MM, MB and BB) and myoglobin were assayed in pericardial fluid. When the results from Copenhagen and Granada were compared, there was absolute concordance in 96 cases, discrepancy in 53 and one case was inconclusive. After studying the circumstances of death, the number of discrepancies were reduced to 20, so that concordance was reached in 86% of all the cases. The results show that the combination of different methods leads to a diagnosis of myocardial infarction in far more cases than with morphological or biochemical methods alone.