—In this paper, we consider a dynamic system composed of several Wireless Body Area Networks (WBANs) interacting with the surrounding environment, forming Body-to-Body Networks (BBNs). In this dynamic BBN system, we analyze the joint mutual and cross-technology interference problem due to the utilization of a limited number of channels by different transmission technologies (i.e., ZigBee and WiFi) sharing the same radio spectrum. To this end, we propose a game theoretical approach to address the problem of Interference Mitigation in BBNs. Our approach considers a two-stage channel allocation scheme: a BBN-stage for inter-WBANs' communications and a WBAN-stage for intra-WBAN communications. We demonstrate that the proposed BBN-stage and WBAN-stage games admit exact potential functions and develop best response algorithms that converge fast to Nash equilibrium points. Finally, numerical results show that the proposed approach is indeed efficient in optimizing the channel allocations in BBNs while using different transmission technologies. Index Terms—Body-to-Body Networks, 2.4 GHz ISM band,