Recent studies suggest that granulocytes (PMNs) play a role in the pathogenesis of acute and chronic myocardial ischemia and extension of myocardial injury. Rabbit-derived antiserum-dependent reduction of circulating PMNs in the dog or using monoclonal antibody anti-CD11b/CD18 of PMNs resulted in smaller myocardial infarcts. Experience in humans shows the modification of PMN function in angina and during myocardial ischemia. In our studies, patients affected by coronary artery disease presented an increase in granulocyte aggregability in coronary sinus and showed a related higher expression of CD11b/CD18 in coronary sinus with respect to aorta leukocytes. The potential role of this modification of PMNs was analyzed.