The possible consequences of the progressive 'ageing' of the immune system are the increase in autoimmune phenomenon, incidence of neoplasia and predisposition to infections. This review analyses the clinical expression of the systemic autoimmune diseases in older patients, focusing on three specific characteristics: the frequent atypical presentation of autoimmune diseases in the elderly, the higher morbidity and mortality of these patients and the frequent association with neoplasic processes. The study of autoimmune manifestations in elderly populations should be considered a priority for future medical research because of increasing life expectation, especially in developed countries.