A new adaptive H∞ anti-synchronization (AHAS) method is proposed for chaotic systems in the presence of unknown parameters and exteal disturbances. Based on the Lyapunov theory and linear matrix inequality formulation, the AHAS controller with adaptive laws of unknown parameters is derived to not only guarantee adaptive anti-synchronization but also reduce the effect of exteal disturbances to an H∞ norm constraint. As an application of the proposed AHAS method, the H∞anti-synchronization problem for Genesio-Tesi chaotic systems is investigated.