Nowadays, large international tour operators, play an important role in tourism distribution channels. They can significantly affect international tourism flow and dominate accomodation establishments and other businesses particularly in mass leisure tourism. Through mergers and acquisitions in tourism industry market structure also changes. This study is supported by secondary research focusing on mass tourism distribution channels and the pricing problems arising between tour operators and accomodation establishments. First of all, vertical and horizontal integration in tourism industry is stated through TUI Group and Thomas Cook Group cases which are two of the largest tour operators in Europe. Afterwards, bargain power of tour operators over accommodation establishments is tried to expose. In conclusion, some recommendations are given in the light of literature.