In this paper, a robust variable structure tracking controller is designed for the mixed tracking control of highly nonlinear rigid robot manipulators for the first time. The mixed control problem under consideration is extended from the basic tracking problem, with the different initial condition of both the planned trajectory and link of robots. This control problem in robotics is not addressed to until now. The tracking accuracy to the sliding trajectory after reaching is analyzed. The stability of the closed loop system is investigated in detail in Theorem 2. The results of Theorem 2 provide the stable condition for control gains. Combing the results of Theorem 1 and Theorem 2 gives rise to possibility of designing the improved variable structure tracking controller to guarantee the tracking error from the determined sliding trajectory within the prescribed accuracy after reaching. The usefulness of the algorithm has been demonstrated through simulation studies on the mixed tracking control of a two.link robot under parameter uncertainties and payload variations.