The aim of this review is to explore the available evidence concerning the relationship between the different parameters of the complete blood count, its pathophysiological changes and cardiovascular disease, specifically focusing on the acute ischemic setting. Erythrocytes, leukocytes and platelets undergo significant and more or less durable changes over time in response to conditions of systemic inflammatory, infectious and neoplastic disease. This is the reason why blood cell count parameters can (and should) be implemented in the global assessment of the patient with acute coronary syndrome.From the literature review it emerges that anemia and thrombocytopenia have an independent negative prognostic role in the medium and long term, being markers of the overall frailty of patients with ischemic heart disease. On the other hand, essential thrombocythemia and polycythemia vera, two chronic myeloproliferative neoplasms, are characterized by an important increase in thrombotic risk. Both conditions are given a brief description for the particular importance of the close collaboration between cardiologists and hematologists in the diagnosis and treatment of these diseases in the context of ischemic heart disease.