Reissner's plate theory assumptions are chosen to approximate the stress field in which the longitudinal stresses are assumed to vary linearly along the plate thickness. For balanced, symmetric, laminates, a stiffness may be taken as the linear average of the corresponding ply stiffnesses. In that case, only 4 laminate stiffness moduli with simple stress strain relations can be utilized. Using the average laminate properties and following the variational analysis, the assumed stress functions and the corresponding displacements can be obtained. As a numerical example, we consider the problem of cylindrical bending of a symmetric cross-ply laminate, consists of 3 layers of graphite/ poxy unidirectional composites. For relatively thick laminates, where the classical plate theory gives a very poor estimate, our results are in a good agreement with the exact el-asticity solution, specially for the deflection and transversal stresses.