It is generally known that the market represents the overall relationship between supply and demand. The relations between these two are constantly intertwining and are constantly influenced by different factors. Depending on their relationship as well as on factors specific to a particular economy, there are different market conditions, such as: monopoly, oligopoly, limited oligopoly, limited competition, perfect competition, etc. The liberalization of the domestic oil and oil derivatives market represents an open space for creating a high-quality competitive relationship. However, the course of strengthening the competitive relationship should be carried out considerably faster. Market conditions and competitiveness are in practice determined by the concentration in the observed market. Competition is in a particular relevant market expressed by a number of concentration indicators. Thus, an important aspect of the analysis of competitiveness intensity in the domestic oil market is measuring the concentration of supply, which will be analyzed in this paper. It can be said that every market is characterized by a certain level of competitiveness among market participants, and through these competitive relationships, their market power permeates. The research uses concentration indicators to show the concentration in the domestic oil and oil derivatives market, its current features and also to analyze the potential of strengthening the competitive relationship in the future.