In laminated composites made of fibre-reinforced polymers (FRP), the separation of layers, also known as delamination, is a common cause of failure. In this study, the free and forced vibrations of an FRP composite plate with a circular hole were affected by delamination. To solve the numerical method, the layerwise theory (LWT) using finite element (FEM) methods and simulated delamination using the ‘constrained mode’ was adopted. The results reveal that the magnitude of delamination has a considerable impact on the natural frequency, stress concentration, and impedance. Copyright © 2023 Inderscience Enterprises Ltd.