The engineering structures may be subjected to the dynamic loads such as blast. Therefore, in the design of such structures, the effect of the blast loading should be taken into account. Several studies are reported on both free vibration and dynamic response analysis of isotropic, orthotropic and laminated composite plates subjected to air blast loading. In all these studies, only the effect of the blast is taken into account. However, because of the initial situation, in-plane forces may exist and may affect the dynamic response of the plate subjected to the blast loading. In this study, a closed form solution is presented for the simply supported laminated composite plates subjected to a combined loading case which includes both the blast and the in-plane forces. In-plane stiffness and inertia effects are considered in the formulation of the problem and transverse shear stresses are ignored. The geometric nonlinearity effects are taken into account by using the von Kármán large deflection theory of thin plates. Approximate solution functions are assumed for the space domain and substituted into the equations of motion. The Galerkin method is used to obtain the nonlinear differential equations in the time domain. The finite difference method is applied to solve the system of coupled nonlinear equations. The displacement-time and strain-time histories are obtained for different combined loading configurations.