The centralization the corporate structural system inherited from the planned economy acts as an impediment to market competition, so that many of the big, artificially created state-owned firms have to be broken up. An active part in doing so has to be played by the state, through the Economic Competition Office as 'guardian' of competition. The logic is clear, but a matter of dispute theoretically and in practice. The article presents the theoretical dilemmas of demonopolization that appeared with the change of system and shows what attempts were made to resolve them through competition regulation and the activity of the Competition Office. It emerges from the analysis that the main role in building up the structural conditions was not played by the Competition Office, which declined the task of inspecting the inherited structure and the privatization decisions, seeing it as economically and politically delicate. As for the small number of merger decisions connected with privatization that it took, they were handled in a legal fashion, but most of the sales and take-overs were simply permitted, not always for consistent reasons.