Organizational culture as a complex system is elaborated in more detail in this paper. The elements and models of organizational culture, as defined by individual authors and the types of organizational culture defined by Cameron and Quinn, are described in more detail. This paper and research on the organizational culture of Croatian Post is based on Cameron and Quinn’s definition of the four types of organizational cultures, consisting of a clan culture, adhocracy culture, market culture and hierarchy culture. Also, the same authors have developed an instrument to measure organizational culture, i.e., the OCAI instrument, which was used for research in this paper. The aim of this paper is to point out the importance of organizational culture in public companies, given that organizational culture is associated with the successful implementation of an enterprise’s strategy, its efficiency and productivity. This is equally important for the general public as well as for private companies. The specificity of the public sector and public enterprises, in regard to organizational culture, is overcoming hierarchy culture and centralization of power. Previous research has shown that public enterprises are dominated by hierarchy culture. Change of the organizational culture is driven by market influences, competition, and conditions that change the market order. Besides a dominant hierarchy organizational culture, in the case of Croatia Post Plc, they also developed in a market and competition culture, which is externally focused. The strategy of Croatia Post is linked to the creativity and innovation of improving its core business. Such a strategy requires determining whether it is better to strive for an adhocracy culture that fosters creativity, innovation and flexibility with decentralization of power. It is therefore important that senior management possesses instruments to measure organizational culture and be familiar with its concept and importance. Only in this way can management coordinate its entire organization with the strategy, and achieve its goals in an efficient and productive way.