Recently ageing has become an important issue because of the dramatic changes in life expectancy. 'Ageing' at the individual level (senescence) is a biological phenomenon common to all high organisms. There is a strong relationship between ageing, inflammation, response to infection, and the progression of chronic inflammatory diseases. In fact, inflammation is necessary to cope with damageing agents and is crucial for survival. But chronic exposure to a variety of antigens for a period much longer than that predicted by evolution, induces a chronic low-grade inflammatory status that contributes to age-associated morbidity and mortality. Probably there is a final common pathway interaction of multiple factors that alters the microenvironment of an acute response to infection that, together with accumulation of anergic/nonresponse T and B cells, results in crossing the threshold of host resistance, resulting in the marked increase in common infections, susceptibility to epidemics, the poor vaccine response, and the occurence of some chronic diseases in elderly.