Abstract Objective Myocardial hypertrophy results in increased levels of cardiac biomarkers in healthy individuals and in patients suffering from acute myocardial infarction. The influence of cardiac mass on postoperative cardiac biomarkers release remains unclear. This study investigated the correlation between myocardial mass and the release of high-sensitivity cardiac Troponin T (hs-cTnT) and creatine kinase (CK) MB after isolated aortic valve replacement or bypass surgery. Methods Myocardial mass of a consecutive retrospective series of patients was measured automatically using preoperative CT scans (636 patients, aortic valve replacement = 251; bypass surgery = 385). Levels of cardiac biomarkers were measured before and serially after surgery. Spearman and Pearson correlation and a multivariate regression model was performed to measure the degree of association between myocardial mass and the release of hs-cTnT and CK-MB. Results Patients were divided into three tertiles according to their myocardial mass index. Higher biomarker levels were measured preoperatively in the upper tertile of patients undergoing aortic valve replacement (p = 0.004) or bypass surgery (p < 0.001). Patients with different heart sizes showed no differences in postoperative biomarker release neither after aortic valve replacement nor bypass surgery. No statistical significant correlation was observed between myocardial mass index and postoperative release of hs-cTnT or CK-MB in any subgroup (ρ maximum 0.106). Conclusion Postoperative biomarker release is not correlated with myocardial mass. Patient factors leading to increased postoperative biomarker levels need to be elucidated in future studies.