This paper presents a research study on Business Network (BN) approach within Small and Medium Enterprises (SME) based on the customer´s buying behaviour. We believe that the interconnection of BN, SME and buying behaviour is not sufficiently explored and there is a need for further studies in this respect. The main focus of this study is the explanation of customer´s buying behaviour in Business to Business market (B2B) which is motivated by customer´s effort to find a solution to his/her problems of rationalization or development. One of the major existing problems for SME is lack of resources (financial, human, technological) needed for the implementation of customer requirements (customer purchase). Lack of resources can be used from company´s Business Network of suppliers and customers. Therefore, not only it is necessary for SME to know their BN and develop relationships with their own suppliers and customers, but also with suppliers of their customers. Using BN approach has resulted in creating strong relationships in BN, thus building a stronger network and gaining a competitive advantage for SME. The BN approach was applied in the market of manufacturing plastics companies which face great competition from SME in Zlín region.