The dynamic stability behavior of laminated composite shells subjected to hygrothermal loadings are studied in the present investigation. A simple laminated model is developed for the vibration and stability analysis of laminated composite shells subjected to hygrothermal conditions. A computer program based on FEM in MATLAB environment is developed to perform all necessary computations. An eight-node isoparametric element is employed in the present The analysis with five degrees of freedom per node. Element elastic stiffness matrices, mass matrices, geometric stiffness matrix due to mechanical and hygrothermal loads and load vectors are derived using the principle of minimum potential energy. Quantitative results are presented to show the effects of curvature, ply-orientation, degrees of orthotropy and static load factors of laminate on dynamic stability of composite shells for different temperatures and moisture concentrations.