This paper presents a system developed for on-line vibration control on a turning lathe. Relative vibration between the workpiece and the cutting tool is sensed with the help of a bifurcated bunch of optical fibres which is then phase shifted, amplified and fed back to a specially designed piezoelectric vibrator supporting the tool. Whenever a vibration occurs, leading the machine tool-cutting process system to instability, the closed-loop feedback contour, with the help of the vibrator-exciter, generates an equal and opposite force to stabilize the vibration. Results obtained by mathematical modelling and experimental investigations indicate a significant improvement in the dynamic characteristics of the machine tool resulting in considerably higher productivity, accuracy and finish. © 1997 Elsevier Science Ltd.