Flutter-type instability of cross-ply shear deformable composite flat panels exposed to a supersonic flow is analyzed. The two-dimensional static aerodynamic approximation and a higher order transverse shear deformation theory for the structural plate model are used. Comparisons of the results obtained in this framework with those derived within their first order transverse shear deformation and classical (Kirchhoff) counterparts are presented and a number of conclusions concerning their range of applicability are outlined. The results underline the strong effect played by transverse shear deformation and transverse normal stress, as well as by the higher order effects on the flutter instability of panels made of advanced composite materials. © 1990.