This paper presents evidence and suggestions from the IFCC C-SMCD on the use of biochemical markers for the triage diagnosis of acute coronary syndromes. There is general agreement that both 'early' and 'definitive' biochemical markers are necessary and that these assays must be available with a turnaround time of 1 h or less. Currently, myoglobin is the marker that most effectively fits the role as an 'early' marker, whereas 'definitive' markers are cardiac troponins. Since the sensitivity of the initial electrocardiogram is only 50% for detecting myocardial infarction, the use of biochemical markers may significantly contribute to the early diagnosis. New sensitive biochemical markers, particularly the cardiac troponins, are presently the best criterion to detect the presence of small myocardial cell damage. Two decision limits are probably needed for the optimum use of troponins: a low abnormal value suggesting the presence of myocardial damage and a higher value suggesting the diagnosis of myocardial infarction. Additional studies should be performed to establish limits for each commercially available assay. Finally, it is recognized that there is no need for the use of any biochemical marker when the clinical diagnosis is unequivocal, other than for diagnosing reinfarction, estimating the infarct size, and monitoring thrombolytic therapy.