The anemia found in patients with chronic infectious, inflammatory, and neoplastic disorders, known as the anemia of chronic disease (ACD), is one of the most common syndromes in medicine. A characteristic finding of the disorders associated with ACD is increased production of the cytokines that mediate the immune or inflammatory response, such as tumor necrosis factor, interleukin-1, and the interferons. All the processes involved in the development of ACD can be attributed to these cytokines, including shortened red cell survival, blunted erythropoietin response to anemia, impaired erythroid colony formation in response to erythropoietin, and abnormal mobilization of reticuloendothelial iron stores. In this review, advances in the understanding of the diagnostic, pathophysiologic, and therapeutic aspects of this syndrome are summarized.