This paper shows the design and implementation of a fuzzy control system used to reduce the vertical motion of a TF-120 fast ferry. The system increases the comfort of the passengers and crew by reducing the main cause of seasickness. The aim of this controller-which is based on a fuzzy model of the ship behaviour-is to decrease the pitch acceleration by controlling the position of some actuators and varying their working angles. Experiments have been carried out on a ship scaled-down replica. The motion sickness incidence has been evaluated and results have proved to be highly satisfactory. (C) 2004 Elsevier Ltd. All rights reserved.