Acute chest pain patients without ECG-signs of acute myocardial infarction (AMI) on admission need to be earlier and better diagnosed to reduce use of expensive intensive care beds and to treat more patients with acute recirculation therapy. We investigated whether total CK-activity, CK-MB mass, CK-MB2, myoglobin, cardiac troponin I (cTnI) and T (cTnT) measured in venous blood on admission and after 1 and 2 h could be used to identify or exclude acute myocardial damage (AMD) in 22 acute chest pain patients without ECG-signs of AMI admitted to hospital within 6 h after onset of pain. Increases in CK-MB mass, CK-MB2, myoglobin and cTnI identified AMD in three patients classified retrospectively as AMI. Likewise, CK-MB mass, CK-MB2, cTnI and cTnT increased with time in three of seven patients classified as having unstable angina pectoris. CK-MB2 and cTnI increased with time in two patients with tachycardia belonging to the other heart disease group. The remaining seven patients of the non-heart disease group showed no change in any of the cardiac markers. Thus, early serial measurements of selected cardiac markers appear useful in identifying or excluding AMD 3 h after admission in these acute chest pain patients.