© 2015, Springer Science+Business Media New York. As an enabling technology for dynamic spectrum access (DSA), cognitive radio (CR) is widely regarded as one of the most promising technologies for future the fifth generation (5G) wireless communications. Although there have been significant prior researches to combat interference on primary users (PUs), the problem of mitigating mutual interference between secondary users (SUs), -which is tightly coupled with SU’s spectrum leasing- is still not understood well. This paper proposes a DSA algorithm based on game theory, which jointly performs spectrum leasing and interference mitigation among SUs. The problem is modeled as an oligopolistic competition using Stackelberg model. We have carefully studied the SU’s spectrum utilization behavior with respect to various criteria of the proposed game theoretic model. Simulation results shows that, Compared with Cournot game model, the proposed scheme enables SUs to efficiently utilize the licensed spectrum shared with PUs in a dynamic environment while maximizing the spectrum utilization.