Blood was collected on admission and after 1-2 h in 130 consecutive patients admitted with typical chest pain in order to assess the capacity of myoglobin, fatty-acid-binding protein (FABP), CK-MB mass, and troponin I (TnI) in the early identification of acute myocardial infarction (AMI) without ST elevation. Using the maximum value within 6 h of onset of symptoms, AMI was detected with a 90-95% sensitivity and a 81-94% specificity by FABP at a cut-off level 8-12 midrog/l, or 81-86% and 89-93%, respectively, by myoglobin at a cut-off level 70-90 microg/l. CK-MB mass and TnI had low sensitivity, albeit very high specificity. As almost all AMI patients were identified within 6 h, serial measurements of FABP or myoglobin ruled out AMI with a very high degree of certainty. Due to the low prevalence of AMI (16%), the positive predictive values were modest (47-73%), yet increasing the probability of AMI by a factor 3-4. Myoglobin and FABP are very useful markers in the early triage of chest pain patients.