Oxidative stress plays a key role in development and progression of cardiovascular diseases and it is correlated with left ventricular dysfunction and heart failure (HF). Oxidative environments lead to the formation of intra- and intermolecular disulfide bonds, as well as to plethora of other reversible and irreversible oxidative amino acid modifications, affecting the functionality of the proteins. Here we report that heart failure due to ischemic cardiomyopathy (ICM) or dilated cardiomyopathy (DCM) is correlated with increase in oxidative stress compared to non-failing control hearts, manifested through decreased GSH/GSSG ratio in failing heart tissue samples and adaptations of cardiac redox proteome which occur in correlation with two different heart pathologies.