An analytical and experimental investigation was carried out to determine the buckling loads of hyperboloidal shells with different geometries subjected to the axisymmetric loadings of external pressure and axial compression. Sander's thin shell equations were used in conjunction with the finite element method to determine the bifurcation buckling load of the shell. The experimental program yielded data on the instability behavior of hyperboloidal shells subjected to combined loadings. Molded PVC specimens were used in the experiments. Shell specimens were: (1) Clamped on both ends; and (20 clamped on one end and free on the other end. The experimental data were found to be in good agreement with the analysis for all types of loading conditions.