This paper investigates the problem of sliding mode control for stochastic Markovian jumping systems, in which there may happen actuator degradation. By on-line estimating the loss of effectiveness of actuators, an adaptive sliding mode controller is designed such that the effect of the actuator degradation can be effectively attenuated. Besides, both the reachability of the specified sliding surfaces and the stability of sliding mode dynamics are ensured despite the actuator degradation and Markovian jumping. Finally, theoretical results are supported by numerical simulations. (C) 2013 Elsevier Ltd. All rights reserved.