The aim of this paper is to quantify service use and costs of supporting frail older people at home in the community, using data collected in a longitudinal multicentre stratified randomised study for 1055 mentally frail, physically frail, and mentally and physically frail subjects. Average costs per person per week were found to total 64.45 Pounds Sterling, with a small number of services accounting for a large proportion of the total costs. The level of services offered by the nonstatutory voluntary and private sectors was found to be small. To highlight issues for policy makers, the extent of cost variations between a number of different subgroups were calculated. These bivariate analyses revealed substantial variation in costs, especially according to household structure, type of frailty, whether admission to continuing care accommodation occurred and survival. Multiple regression analysis demonstrated that 26% of the variation in log average weekly costs could be explained by a number of socio-demographic and health status variables. A particularly close relationship was observed between costs and whether admission to continuing care accommodation occurred, highlighting a need for policy-makers to examine the nature and scale of provision of alternative community based care packages. The results demonstrate that descriptive cost data such as those presented can provide information useful to the planning process, enabling more informed choices to be made over the provision of services for particular groups of people.