Air transport is one of the industries where strategic alliances are most common. While alliance strategies by airlines are widespread, the performance and sustainability of alliances is currently in debate. However, the importance of the level of integration for the benefits from mergers and alliances in the literature is an important topic discussed. In this study, we relate the sustainability of alliances to the benefits gained from that cooperation and aimed to demonstrate the importance of the level of integration on the alliance benefits in the airline industry. To achieve this aim, after a comprehensive literature, we conducted a research on three global airline alliance members. The study comprises 26 international airlines who are members of one of global airline alliances - Star, Sky Team and Oneworld. The results suggest that there is a significant and positive relationship between level of integration of airlines to the global alliance and the alliance benefits gained from the alliance membership.