Experimental studies on the adaptive vibration control of composite beams with a piezoelectric actuator have been performed using a neural network controller. We experimentally investigated the variations in natural frequencies and actuation characteristics of the composite specimens according to delaminations in the bonding layer. Numerical simulation has been performed for adaptive vibration controls of the composite specimens with delaminated piezoclectric actuator using the neuro-controller. A digital signal processor (DSP)-based hardware for the real-time adaptive vibration control experiment was prepared. Using the neuro-controller, the adaptive vibration control experiment has been performed. The vibration control results show that the present neuro-controller has good performance and robustness with respect to the system parameter variations. (C) 2000 Academic Press.