This study evaluates the reliability of the discharge status variable in health insurance claims for identifying in-hospital patient deaths. This study used 2002 national health insurance claims and the cause of death statistics from Korean national statistical office. The Study data set included acute myocardial infarction (AMI) and coronary artery bypass graft (CABG) surgery patients in 133 general and tertiary hospitals. The gold standard containing patient death information was made and then compared with that of claims data. The hospitals were classified into four groups based on the number of deaths in each hospital. Simple kappa coefficients were calculated to evaluate the agreements of patient deaths between the gold standard and the insurance claims. CABG (83.9%) showed higher agreements than AMI (73.0%) in matched in-hospital patient death information between data sets. Simple kappa coefficients of CABG (0.63) and AMI (0.59) showed moderate or good agreements. The agreements, however, varied depending on the disease or hospital types. The fact that the agreements are only moderate to good indicates that the accuracy of in-hospital death information in claims is not high. If the variable is used to identify patient deaths, it may mislead people. Therefore, efforts should be made to improve the reliability of the discharge status variable in health insurance claims.