A partial hybrid plate element vibration analysis is established for orthotropic laminated plates. The inertia effect is considered by adding kinetic energy to the modified Hellinger-Reissner principle. The dynamic governing equations of the plate are then derived variationally. As the through-thickness effect is properly accounted for by assuming only transverse shear stress fields, the natural frequencies are therefore accurately calculated. The validity of the present formulation is determined via problems for which the exact solutions and numerical results are available. Excellent accuracy and fast convergence are observed.