Bending analysis of rectangular orthotropic plates due to lateral loads has been considered by many writers. A small initial curvature has no effect on the bending of a plate due to the action of a lateral load, and the final deflection curve may be obtained by superposing the ordinates due to the initial curvature on the deflections calculated as for a straight plate, but when the plate is subjected to compressive forces acting in the plane of the plate, the initial curvature influences considerably the deflections produced by these forces. The analogy between bending of orthotropic plates with small initial curvature and the plate vibration is established here by expressing the ratio of the initial deflection to the additional deflection in terms of the frequencies of free vibration.