Demographic aging is now well established. Thus, infections in the elderly will continue to become an increasingly important public health issue. Infections are not only more frequent in the elderly, but they also have distinct properties. Infectious diseases of the elderly are distinct with respect to epidemiology, clinical presentation, treatment, and outcome. Theses specificities are explained through a variety of factors, including the ageing process itself, but also comorbidities, sociological and environmental factors. Geriatric infectious diseases is likely to develop as an increasingly important branch of geriatrics and infectious disease.