The main aim of this paper is to identify and evaluate medium- and long-term market effects of the disinvestment processes made by the private equity funds in the form of initial public offering on the Warsaw Stock Exchange. The empirical studies have failed to positively verify the assumptions contained in the research hypothesis that, in the medium-and long-term rates of return on shares of private equity
backed companies exceed the rates of return on initial public offerings of other companies. The observed differences in the rates of return on stocks in both groups of companies were not sustainable in the adopted research perspective, as well as were characterized by the lack of statistical significance. The empirical studies have been carried out on the group of 52 companies that the first listing on the Warsaw Stock Exchange had taken place between 2002 and 2010.