Declining fertility and infant mortality has caused the population in many developing countries to age. Population ageing can produce a rapid shift in the predominant public health problems from infant mortality and infectious diseases to chronic disease mortality at later ages. Designing public health strategies to deal with the health consequences of population ageing in developing countries is difficult both because of a remaining burden of infectious diseases and because of changes in life style associated with economic development that may raise chronic disease risks. Because there are few longitudinal studies of chronic disease risks in developing countries, we investigate the use of a planning and forecasting model, which combines data from multiple sources, in six developing countries.