The objective of this paper is to investigate the interactions linking models and experiments in the dynamics of composite structures. It concerns the validation of predictive models and the characterization of materials. The analysis is supported by the synthesis of four studies and two industrial applications. The numerical models essentially use the finite element method and the experimental modal analysis focuses on natural frequencies, mode shapes, frequency response and damping. In conclusion, certain points of the mixed approach are highlighted and it appears in particular that reciprocation between simulations and tests is frequent and often necessary to improve the efficiency of the design process. (C) 1998 Elsevier Science Ltd. All rights reserved.