The aerospace industry finds a wide application of thin cylindrical shells. Cutouts in various structures are also an important application particularly in aircraft and aerospace industry which is a significant area of research today. The load-carrying capacity of these structures is determined by the buckling characteristics of that specimen mainly in aircraft since the primary cause of failure is elastic buckling. Even though cut-outs in these structures decrease the buckling strength due to the stress concentrations, it cannot be avoided in many engineering applications particularly in aircraft components. Cylindrical shells made of mild steel are considered for the study. In this paper the buckling behavior of the shells made without cutouts, with cutouts, and with semi cutouts of constant diameter are studied.