Common prognoses for trends in life expectancy just extrapolate historical mortality trends: These centenarian trends take insufficient account of the increasing speed of mortality reduction in higher age groups in the last twenty years. Therefore these centenarian trends have to be regarded as too pessimistic in the short-term. On the other hand, these trends are based on constant mortality reduction in the long-term. With regard to new biological theories these trends are too optimistic in the long-term. Investigation of »avoidable deaths« allows further conclusions to be made for the expected trends in mortality. A further substantial reduction of mortality depends, not so much on the progress of curative medicine (at least not for the young and middle ages), but, on the realisation of definable preventive interventions, concerning societal and individual factors. Finally forecasts of the life expectancy trends have to take into account potentially life-prolonging indirect effects of health services and socioeconomic factors.