This paper explores the impacts of demographic change on national saving and international capital flows. Introducing demographic structure and pension systems into a four-stage overlapping-generation model of a small open economy, the paper derives analytical solutions which link a wide range of factors to national saving and the current account. This framework enables tractable analysis of the effects of various demographic shocks on national saving and external balances, and also of the interaction between demographic shocks and productivity growth and pension systems. The demographic impacts on national saving and capital flows depend on the nature of demographic shocks (fertility or mortality; transitory, permanent or persistent) and on the stage of demographic shocks, as well as productivity growth and pension structure.