This paper describes the design and implementation of a fuzzy controller for autonomous mobile robots. The tool Xfuzzy 3.0, developed at the IMSE (Instituto de Microelectrónica de Sevilla) has been used to design a controller for the Romeo 4R autonomous vehicle designed and built at the "Escuela Superior de Ingenieros", University of Seville. The paper presents the design of the controller and real experiments with Romeo 4R demonstrating the efficiency of the controller.This work has been partially supported by the Spanish CICYT Projects TAP99-0926-C04-01 and TIC2001-1726.Peer reviewed