Game theory is the mathematical study of conflict of interest situations. As such, it is applicable not only in parlor games (hence its name), but also in military and economic situations and, to a lesser extent, in situations in other social sciences. In the business world it is important for a company to successfully create a certain competitive advantage compared to the other companies operating in the same market and are competing for the same consumers. The answer to the question why some companies are more successful at achieving this than others may lie in the way the managers of said companies make strategic decisions relevant the their companies future. In making such decisions a number of things can be helpful, their psychological and emotional stamina but also their preparedness, and also knowledge and use of mathematical models. Game theory consists of several mathematical models used by companies to make optimal strategic decisions, in relation to other companies' decisions, which will potentially lead to strengthening the company in the market and finally its business maximum. Purpose of this paper is to determine the importance and advantage of using game theory in certain marketing areas, explore the role of game theory in optimal decision making in the field of companies marketing, that is, how a company must take into account how the competitors and consumers will respond to their strategies.