A modified robust model reference adaptive controller is proposed to deal with the unguaranteed transient performance problem in standard robust model reference adaptive control. An ??_∞ compensator is introduced as an additional item in nominal robust adaptive control to attenuate the adverse effects on tracking performance caused by parameter estimation error and bounded uncertain disturbance. The theoretical analysis and simulation results show that the proposed controller not only can maintain the ideal properties of the standard robust model reference adaptive control, but also greatly improve the transient performance of the closed-loop system through designing a proper ??_∞ compensator. Furthermore, the amount of the transient performance improvement depends on the performance level of the ??_∞ compensator