This paper examines the various theories of intergenerational justice and its implications in the practical context of pension systems. In this context the sustainability of the system appears to be compromised by demographic projections. This fact has an unquestionable relevance for the future of this very important public service and the intergenerational commitment that this implies. In this sense if a pension system wants to be fair it has to look in three directions: pensioners, workers and future generations. So, a (...) liberal-egalitarian theory becomes necessary to share the risks of demographic and financial shocks between different generations and to reduce inequality as much as possible. (shrink)