Cylindrical shells are commonly used in various industries such as manufacturing airplanes, missiles, pipelines, bicycles, submarines, different automobile devices, decorative structures for buildings etc. They have extensive applications in industries because of their low weight, high resistance and ease of use. While working, these structures undergo various forces such as axial, torsional, internal pressure, or a combination of different loadings. Cylindrical shells with different openings are under the effect of tension concentration and instability of structure due to their geometric disconnections. The study of pore effects on load carrying and buckling behavior of cylindrical shells has been, and still is, among the manufacturers and designers’ concerns. In this paper, the buckling of cylindrical shells with seam, with lozenge or circular openings under axial load has been investigated using numerical and laboratory methods. The shells are of steel (standard: No: 1.0110 ST 37, DIN) which is one of the most common materials used in various industries including traditional and industrial construction, gas, oil and petrochemical industries. The effect of different openings on the buckling load of shells has been analyzed, and the obtained results have been compared with those obtained in the lab using Abacus software.