This paper proposes a new algorithm for achieving discrete-time sliding mode for single input single output systems with bounded matched uncertainty using output feedback. The concept of periodic output feedback is used here. It has been shown that, when the output of the uncertain system with matched uncertainty is sampled slower than the input, there exist a discrete-time quasi sliding mode. The method is very general and is applicable to any controllable and observable linear time invariant single input single output system. The proposed technique is illustrated with numerical examples. Copyright © 2012 Inderscience Enterprises Ltd.