In aged populations, infectious diseases are generally more serious and cause higher mortality. This has been attributed to a decline in the functional activity of the immune system. Many factors have been implicated, such as thymus involution and progressive impairment of the tissues and cells involved in the generation of immune response. One of the key constituents of the immune system are macrophages. In this review we present data produced over last 10 years about the effects of aging on macrophages.