The introduction of new biochemical markers for myocardial damage in the recent years and different application of these methods in different centres may have an impact on the diagnostic criteria for acute myocardial infarction (AMI). By means of a questionnaire we studied the diagnostic criteria for AMI in relation to the use of different biochemical markers among 78 Danish hospitals. There were large variations with regard to the choice of cardiac markers and diagnostic values for different markers. CK-B is the cardiac marker mostly used followed by CK-MB. Troponin-T test was used by about 20% of the centres. Many centres are planning to use CK-MB and Troponin-T test. A common national and international policy for diagnosis of AMI in relation to different cardiac markers should reduce these improper differences.