Inclusion of various defects, e.g. imperfection or notches, in cylinders during their service life is expected and identifying of the load bearing capacity of the structure in the presence of those imperfection and damages are necessary. In the present paper, the plastic buckling of notched cylinders is studied experimentally and numerically for various groups of the cylinder dimensions. The study focuses on influences of various characteristics of notches, such as orientation, position and notch length on the buckling capacity of the cylindrical shells. In this direction, the amount of absorbed internal strain energy affected by inserting notch is calculated and compared with intact ones.