This paper deals with markets of imperfect competition. The market is a place where supply and demand meet while there is competition. Market structures are divided into perfect and imperfect competition. Perfect competition is possible only in theory because it requires a lot of manufacturers of the same goods in the market, a lot of customers and unhindered entry and exit from the market, as well as excellent information of customers and manufacturers about market data. Imperfect competition occurs in the market when one of the conditions in a perfectly competitive market is not met. This type of market is very common. In fact, every industry has some kind of imperfect competition. These include a market with different products and services, prices that are not determined by supply and demand, competition for market share, customers who may not have complete information about products and prices, and high barriers to entry and exit. Types of imperfect competition are monopolies, duopolies, oligopolies, and monopolistic competition. The paper analyzes and defines market structures with an emphasis on imperfect competition. In addition to the definitions and theoretical basis of each market structure, examples are given in the Republic of Croatia for each form of market structure of imperfect competition.