Abstract— The aim of the present paper is to investigate the effect of web openings on the lateral-torsional buckling resistance of castellated beams by using both analytical and numerical methods. The analytical approach is developed based on the principle of minimum potential energy, meanwhile elastic and inelastic numerical solutions obtained using ANSYS software are for the validation of the analytical solutions. The investigations are carried out through the application of uniformly distributed transverse loading on top flange of a castellated beam with common boundary conditions. The developed analytical solutions is can be used for the design and practical use.