The correlation among clinicopathological parameters of myocardial damage was investigated in rats administered a single subcutaneous dose of isoproterenol at 0 (saline), 0.04, 0.4 and 4 mg/kg. Total lactate dehydrogenase (LDH), creatine kinase (CK), and their isoenzymes (LDH-1, LDH-2 and CK-MB), as well as troponin I and tropinin T, were measured 4 h after the administration of the drug. Troponin I was determined by a chemiluminescence method using Bayer Centaur and DPC Immulyze, as well as by ELISA. Troponin T was assayed semi-quantitatively using Trop T Sensitive. A high correlation was found among LDH isoenzymes, troponin I (Centaur) and troponin T. The present result provides a baseline for interpreting changes in the different parameters of myocardial damage assayed by different methods in toxicity studies.