Acute myocardial infarction (AMI) is a myocardial necrosis occurring due to persistent coronary ischemia, in which inflammation plays an important role and heart failure is a common complication. The present work was undertaken to clarify the role of Tumor Necrosis Factor Alpha (TNF-alpha) in acute myocardial infarction (AMI). The study was conducted on 20 newly diagnosed AMI patients and 10 healthy age and sex matched controls. Sequential estimation of plasma TNF alpha level was carried out at admission, 24 and 48 hours post admission using ELISA. AMI patients showed a significant increase of plasma TNF-alpha level on admission, and 24 hours post admission but not after 48 hours. However, a significant increase was still seen at 48 hours post admission in patients with signs of heart failure but not in those without signs of heart failure. A significant positive correlation was found between plasma TNF-alpha level and CPK level at admission. On the other hand a significant negative correlation was found between these 2 parameters at 24 and 48 hours post admission. It is concluded that TNF-alpha may be an early marker of myocardial damage because of the early increase of its level after ischemic injury instead of being late consequence of extensive tissue necrosis. TNF-alpha level may be an important indicator of the severity of AMI and the occurrence of heart failure.