BACKGROUND Cardiac troponins replaced creatine kinase and lactate dehydrogenase isoenzymes as criterion standards for the laboratory diagnosis of myocardial damage. However, there are only few publications on correlations of cardiac troponin T (cTnT) with pathologically determined infarct size which are flawed by insufficient sample size. METHODS In 38 anesthetized wildtype mice, the chest and pericardium were opened and the left descending artery was ligated. After sham operation, all mice recovered. Twenty-four hours after surgical induction of acute myocardial infarction heparinized blood samples were collected, the animals sacrificed and hearts harvested. Plasma cTnT was measured by a quantitative rapid assay using the Cardiac Reader (Roche Diagnostics). The hearts were cut into four transverse sections which were stained with 1.5% triphenyltetrazolium chloride for evaluation of necrosis by computerized planimetry. Pearson correlation coefficients were calculated between histological infarct size and cardiac markers. RESULTS Infarct sizes ranged from 14% to 55% of left ventricle and cTnT concentrations from 3.9 to 14.1 microg/l. cTnT correlated closely with histological infarct size (r = 0.84, p < 0.001). CONCLUSIONS This study for the first time demonstrates a close correlation of cTnT release with pathological infarct size in a suitable experimental model with a sufficient sample size.