The main obligation of open pension funds (OPF), established in Poland in 1999, was to collect and multiply the pension savings of their participants. For this reason, the legal rules governing the investment activities of funds are crucial not only for the functioning of the OPF but also for its members. The aim of this contribution is the revision of changes in the legal regulations governing the foreign investment policy of the Polish open pension funds from the moment they were established in 1999 till the end of 2016 as well as the evaluation of the impact of these changes on investment activities of pension funds and their investment portfolios. The article is based on the analysis of legislation documents and statistics on investment activities of open pension funds published by the Polish Financial Supervision Authority and particular pension funds.