This paper discusses the optimal continuous-time control problem of a class of piecewise affine (PWA) systems, where the switching action of the discrete state is determined at each sampling time according to a condition on the continuous state. Such a system is called here the sampled-data PWA (SD-PWA) system. First, important remarks on the control design of this system via the continuous-(or discrete-)time PWA model are pointed out, which motivate us to use the SD-PWA model. Next, based on the good properties of the proposed model, an optimal continuous-time controller of the SD-PWA systems is proposed. (C) 2003 Elsevier Ltd. All rights reserved.