Anemia is well recognized as a marker of poor prognosis in patients with cardiovascular disease. Despite increasing awareness that anemia is associated with higher mortality, more frequent hospitalization, and worse health status, it remains unclear whether treating chronic anemia improves patients' outcomes. The importance of studying hospital-acquired anemia (HAA), and recognizing which patients are at high risk for developing HAA early in the course of their hospitalization, is underscored by the potential opportunities for HAA prevention and management. This article reviews the incidence of HAA, risk factors for developing HAA, and its relationship with clinical outcomes.