Background : Previous studies have shown that the distribution of older people by living arrangement has changed and that old-age mortality differs by living arrangement. However, how these changes affect the total number of deaths has not been investigated. Objective : Our aim is to differentiate the effects on mortality of the change in the distribution of the population and the change in mortality rates associated with each type of living arrangement. Methods : Continuous observation of the population aged 60 and older for the period 1991-2012 in Belgium provides a unique opportunity to analyze changes in the population and in mortality by living arrangement. A simple decomposition method is used to examine to what extent these changes have influenced the total number of deaths. Results : The distribution of the population by living arrangement and the age-standardised mortality rates by living arrangement have changed remarkably. The overall effects of these changes on the total number of deaths offset each other, whereas the distribution of the number of deaths by living arrangement displays a large variation. Conclusions : This paper shows important changes in the distribution of the population and in mortality rates by living arrangement but only limited change in the total number of deaths. An important change occurred in the distribution of the population by their last living arrangement before death. Contribution : This paper highlights long-term trends in population and mortality rates by living arrangement in older age and also the distribution of the last living arrangement before death, which has important implications concerning care of the most elderly.