The paper presents the importance of horizontal integration in organic farming, according to opinions of the owners of farms specialising in production of organic food raw materials and operating in Warminsko-Mazurskie province in Poland. The research was conducted using both an opinion poll and participant observation among 297 randomly selected respondents. In Poland, organic farming has been developing rapidly in the recent years. The number of both producers of food raw materials, along with the acreage of agricultural area, and of processing plants has been on the increase. Moreover, groups of producers of organic food raw materials are being established. However, commodity production falls behind, and the market for organic foodstuffs is developing slowly. The main factor affecting organic farming is the agro-environment payment scheme. It has been demonstrated that the process of horizontal integration in organic farming also has an important role, since, according to the research, in the opinion of organic farm owners, such a measure is an important factor for organisation of the market for both organic food raw materials and organic food products. It contributes to the concentration of supply, which allows increasing the economic effectiveness of farms owned by members of producer groups through higher selling prices as well as lower prices of the purchase of means of production. At the same time, it allows reducing the prices being offered to consumers. On the contrary, forming associations entails certain limitations which may restrain activities being undertaken by producer groups.