Ligation of the main left coronary artery in mice serves as a model for myocardial infarction (MI). We tested whether plasma concentrations of heart-type fatty acid-binding protein (H-FABP) and/or cardiac troponin T (cTnT) discriminate between infarcted and sham-operated mice and allow estimation of infarct size. Mice were subjected to coronary artery ligation or sham surgery and release curves of H-FABP and cTnT were determined. At 4 h after surgery the mean (+/-SD) H-FABP plasma concentration was 461+/-134 microg/l (n=10) in MI and 185+/-51 microg/l (n=6; P<0.001) in sham-operated mice. By 24 h after surgery H-FABP levels had returned to normal in both groups. cTnT plasma concentrations increased up to 48 h after MI to 13.5+/-6.2 microg/l (n=6; P<0.001) compared with 0.031+/-0.063 microg/l (n=7) in sham-operated mice. Linear regression analysis revealed a significant correlation between plasma H-FABP at 4 h and infarct size assessed 7 days after surgery. Plasma cTnT did not correlate significantly with infarct size. In conclusion, plasma cTnT concentration at 48 h after infarction can be used to distinguish MI from sham mice, whereas H-FABP concentration at 4 h can be used for stratification of animals according to infarct size.