A Quasi-Sliding Mode (QSM) based tracking control method for tackling Multiple-Input Multiple-Output (MIMO) nonlinear continuous-time systems with un-matching system uncertainties and exogenous disturbances is proposed. The presented Repetitive Control (RC) scheme ensures robust system stability when the system is subject to non-periodic uncertainties and exogenous disturbances. The complete rejection of periodic exogenous disturbances and a perfect tracking of non-periodic reference trajectories are achievable. In this paper, a practical application to a mass-spring-damper system is used to illustrate the validity of the proposed QSM based RC method. (C) 2008 Elsevier Ltd. All rights reserved.