In almost all countries around the world, pension systems are based on several pillars. This is also the case of Slovakia with its three-pillar pension system. The paper presents a case study underlying the risks that can seriously affect the amount of future pensions. The case study clearly indicates that current pensions in Slovakia paid under all three pillars do not correspond with the expectations from the implementation of the three-pillar pension system. The aim of the paper is to the risks that can seriously affect the amount of future pensions. Our own contribution is the determination of the amount of pension for a specific pensioner specified in the presented case study. Within the saving phase of pension contributions the development of investment fund returns, the amount of future pensioner´s contributions, as well as administrative costs are analyzed on a monthly basis. The payout phase is modelled using actuarial functions applying the mortality tables of Slovakia.