Immunosenescence is characterized by impaired cellular immune function concomitant with increased inflammatory activity. Immune dysfunction is associated with increased mortality risk in elderly people. An important part of human ageing is characterized by a decline in the ability of individuals to adapt to environmental stress. Exercise has been suggested as a prototype for studying the effects of stress factors on the cellular immune system. Studies of interactions between an acute bout of exercise and immune function may be a useful and an ethically acceptable tool to investigate cell trafficking, immune mobilization/deficiency and the acute phase response during physical stress situations in relation to human ageing. Elderly humans have a preserved ability to recruit T lymphocytes and NK cells in response to an acute bout of exercise. Physical exercise training programs do not result in major restoration of the senescent immune system in humans. However, highly conditioned elderly humans seem to have a relatively better preserved immune system, although it is not possible to conclude if this is linked to training or other lifestyle-related factors.