Immune deficiency is not an age-related process, but rather a progressive process where predominantly cellular immune response is gradually, but never totally, replaced by antibody response. Cellular immune response appears to be associated with the intrinsic mechanisms of pathological aging. Cellular immunity resulting from induction of macrophage stimulation and cytokine secretion appears to involved. These immuno-inflammatory changes mimic the effects of pathological aging in the different organs. Are they essential factors or simply accessory phenomena? Switching towards an antibody response appears to be a mechanism of adaptation rather than a mechanism of deterioration. Immune status provides a good means of assessing general status in an elderly subject. An attempt should be made to identify the cause of any immune deficiency since age is not in itself an underlying cause. Etiological treatment is indicated.