The aim of this study was to determine the clinical relevance of cardiac biomarkers [troponin I and T, creatine kinase-MB fraction (CK-MB) and lactate dehydrogenase (LDH)] in premature calves with respiratory distress syndrome. Seventy premature calves were admitted to the clinic within 24 h after birth. Respiratory distress syndrome was diagnosed in premature calves by clinical examination and venous blood gas analysis. Ten healthy calves, aged 5 days, were used as control. Cardiac troponin I and T were analysed using ELISA and ELFA, respectively. Serum CK-MB and LDH were also analysed in an automatic analyser. The calves had low venous pH, pO(2), O-2 saturation and high pCO(2) values consistent with dyspnoea, hypoxaemia, and inadequate oxygen delivery. Mean serum troponin I, troponin T, CK-MB and LDH levels were increased in the premature calves compared to the control group. In conclusion, the results in this study demonstrated that serum CK-MB, troponin I and troponin T concentrations could be used for evaluating myocardial injury in premature calves with respiratory distress syndrome.