Two nonlinear problems of parametric vibrations of imperfect antisymmetrically laminated angle-ply plates are considered. In the first problem the response of plates subjected to biaxial pulsating loads is studied. The second problem deals with the behavior of the plate initially subjected to axial static loading. In this problem two solutions for the motion due to the subsequent application of the pulsating stresses are obtained based on the nonlinear and linearized equations, respectively. In the last case the problem allows analytical solution. Numerical analysis is presented for both problems considered. © 1989.