This paper discusses the long run effect of changes in the age distribution of Spanish population on the unemployment rate, disaggregated by sex and age segments in the light of cointegration theory given the non stationarity of the series. Four main results are obtained. First, empirical analysis does not provide a clear scheme concerning the long run relationships between population variables and the specificunemployment rates for different groups. Second, as a first approximation one can detect the existence of, at least, one long run equilibrium relationship in all sex-age groups, except for the ones including the middle aged unemployed female workers and oldest unemployed female workers. Third, a more thorough analysis enables us to justify the existence of such long run relationships for the youngest male workers and middle aged male workers. One cannot argue, however, a joint evolution of population variables and the unemployment rates associated with female workers and to the oldest male workers. Fourth, the short run dynamics of unemployment rates for the youngest (male and female workers) and the middle age male workers is affected by the transitory deviations from these long run relationships. Hence, from an applied economics point of view, the result stresses the likely failure of employment policies which do not take into account the heterogeneous composition of unemployed workers. It stresses the need to design particular policies for specific groups of workers depending on their age and sex characteristics.