Sepsis is a serious condition with high mortality, which is frequently encountered in neonatal calves. Cardiovascular abnormalities due to sepsis frequently occur, therefore early diagnosis and treatment of sepsis is of great importance in the survival of calves. Cardiac troponin I (cTnI) is considered to be an excellent biomarker in the diagnosis of cardiac damage due to its properties such as rapid release and high tissue specificity to the heart. The present study aims at evaluating the concentration of serum cTnI and cardiac enzyme activities (CK-MB, LDH and AST) in neonatal calves with sepsis. To this end, 15 neonatal calves with sepsis (sepsis group, SG) and 10 healthy neonatal calves (control group, CG) were used. From serum samples, cardiac enzyme activities (CK-MB, LDH and AST) and concentrations of urea and creatinine (Cr) were determined using an autoanalyzer using commercial kits, while cTnI concentration was determined by the one-step sandwich method of a commercial immunoassay system. The parameters of SG were statistically significantly higher than CG group: total leukocyte (WBC) and neutrophil (NEU) counts (P<0.01), cTnI concentration (P<0.01), CK-MB, LDH and AST activities (P<0.05) and concentrations of UREA and Cr (P<0.001). Sensitivity values for myocardial damage were for cTnI: 100%, CK-MB: 66.7%, LDH and AST: 53.3%. The areas under the ROC curve were 0.98, 0.72, 0.69 and 0.80 for cTnI, CK-MB, LDH and AST respectively. In conclusion, sepsis may cause myocardial damage in neonatal calves. In this study, we have investigated the performances of cTnI, CK-MB, LDH and AST markers in the diagnosis and prognosis of myocardial damage and found that cTnI is superior to other markers based on both inter-group comparisons and ROC analyses. It should be taken into consideration by veterinarians that when endotoxemia develops in animals with sepsis, heart damage can occur which intensifies gradually. Based on the parameters tested in this study, this damage can be best indicated by cTnI. Further studies should be designed with various emerging cardiac parameters, to test their efficiency and sensitivity, such as FAPB3 also known as Hearttype Fatty Acid binding protein. Histopathological examination can also be considered in cases where the animals do not survive.