The ply-drop technique is used to introduce thickness tapering in laminated plates. In addition to optimizing material usage, it tailors the stiffness to meet the functional requirements. The present study reports novel results pertaining to the natural vibrations of thickness-tapered laminated rectangular plates under hygrothermal conditions. The finite element model is developed employing layered tapered plate element based on Reddy’s higher order shear deformation theory. The influence of taper configuration, ply orientation, side to thickness ratio and thermal conditions on the fundamental natural frequency is investigated.