To determine whether there are sex-based differences in serum troponin I (TnI) after cardiac surgery with cardiopulmonary bypass (CPB), excluding patients with perioperative myocardial infarction (AMI) with ST changes (STEMI). No clinically relevant sex-based differences were found in the TnI peaks after cardiac surgery without AMI. Therefore, there is no reason to change the myocardial damage stratification in a sex-specific manner. This confirms the lack of TnI sex differences after cardiac surgery when AMI is not present, but shows a significant difference between men and women in the TnI peak and curve after cardiac surgery when an AMI occurs. The TnI curves reveal a highly-significant sex difference in the STEMI and non-STEMI groups. Men have a higher percentage of AMI (11.7% versus 5.6%), of STEMI (6.0% versus 1.8%) and of non-STEMI (5.7% versus 3.8%). These differences do not seem to be based on previous differences between the patients and had important repercussions in terms of mortality, there being sex differences in the time of ICU stay but not in the mortality in any subgroup.