The purpose of the study was to detect myocardial cell injury in cats with blunt thoracic trauma by use of circulating biochemical markers such as alpha-hydroxybutyrate dehydrogenase (alpha-HBDH), creatine kinase isoenzyme MB (CK-MB), and cardiac troponins I and T (cTnI/cTnT) and their comparison to corresponding ECG alterations. Thirty-one cats with blunt chest trauma due to high-rise syndrome, vehicular accident, or pivot window trauma were evaluated clinically, electrocardiographically, and blood biochemically 12 to 24 hours and 60 to 72 hours after trauma. Data gained from 26 normal cats were used for comparison. Alpha-HBDH, CK-MB, and cTnI were significantly increased 12 to 24 hours after trauma (p less than or equal to 0.01) and then declined (p less than or equal to 0.05). Cardiac TnT was increased in only 6 of 31 cats after trauma. ECG abnormalities were observed in 25 of 31 cats. The ECG alterations found in 10 cats were considered to be significant (ST-segment abnormalities, ventricular premature beats, and AV escape rhythms). Myocardial cell injury is common after blunt chest trauma in cats and may be detected by analysis of circulating cardiac specific parameters. Cardiac TnI is more sensitive to diagnose myocardial injury than cTnT, CK-MB, or alpha-HBDH. There was no correlation between ECG changes and serum cTnI levels.