In this study, it was aimed to determine the effect of diclofenac administration on serum cardiac damage markers in exercised and non-exercised rats. In the study, 28 rats were divided into 4 equal groups. No application was made to control group, while the rats in the exercise group were floated for 30 min in a day. Diclofenac group were received at the dose of 13.5 mg/kg (intraperitoneally) diclofenac once a day, whereas the rats in the Diclofenac+Exercise group were floated for 30 min after than 1 h of administration of diclofenac at the dose of 13.5 mg/kg (intraperitoneally) once a day. At the end of one week, blood samples were taken from by cardiac puncture under general anesthesia and afterwards, rats are immediately euthanized. Rat-specific cardiac troponin I, creatine kinase-MB, lactate dehydrogenase, aspartate aminotransferase, alkaline phosphatase, gamma glutamyltransferase, blood urea nitrogen and creatinine levels were determined in the samples. Cardiac troponin I, lactate dehydrogenase and aspartate aminotransferase levels of Diclofenac group were statistically significantly higher (P<0.05) than the all other groups, however, statistically significant (P<0.05) fluctuations were in the creatinine levels in the experimental groups. In conclusion, it is stated that the diclofenac application may cause heart damage and diclofenac may not increase heart damage when exercised together with ingestion.