The diploma thesis examines the implicit pension debt in the fifteen EU countries. The Holzmann et al. (2011) methodology is applied to show the impact of population ageing on the pension systems in the EU. The implicit pension debts demonstrate the considerable hidden debt burden in the all fifteen countries. The implicit pension debts range in the interval from 47 % of GDP for the Czech Republic to 906 % for Greece. Nine of the analyzed countries record the implicit pension debts in the interval 100 - 300 % of GDP. The sensitivity analysis and the comparison with other studies confirm our findings. The thesis points out sizeable imbalances among the particular countries, genders and age cohorts.