Cardiac troponin T (cTnT) degradation after tissue release is still under debate. Because degradation of cTnT might have consequences on clearance of the molecule from the circulation, but also on the assay performance, the aim of this study was to investigate cTnT release and degradation in serum of AMI patients.Serum samples were collected from 20 patients with AMI diagnosis undergoing rapid revascularization. Intact cTnT and fragments were detected using a combination of immunoprecipitation, SDS-PAGE and Western blotting.The intact cTnT protein was detected only during the first 12 h after the cTnT concentration started to increase above the AMI cut-off value of 0.03 microg/L. Thereafter only fragments with molecular weights ranging from 10 to 30 kDa were detected, with two fragments being most prominent (15 and 25 kDa).Intact cTnT rapidly disappears from the circulation during the early hours after AMI, but immunoreactive fragments remain present longer. The current cTnT immunoassay detects both intact cTnT and fragments.