The objective of this paper is to realize a fuzzy controller for an electro-hydraulic fin servo system of a missile. In this paper, we propose a new fuzzy controller using the phase plane, in order to improve the overall performance of the fin servo system. The design procedure and method of this controller are easy and simple such that performance evaluation can be carried out in a phase plane mapped from a decision rule table. The effectiveness of this control scheme is verified by comparison with a PID and a fixed fuzzy control through a series of simulation studies and experiments. (C) 2002 Elsevier Science Ltd. All rights reserved.