Overall imperfection method for flexure and compression steel beam-columns. The principles and applications of the overall (global) imperfection method (OIM) for beam-columns are presented in this paper. The buckling resistance of a beam-column member is determined by the resistance of its critical cross-section taking into account second-order effect of the eigenform equivalent initial imperfection. The maximum amplitude of this initial imperfection, in the shape of elastic buckling mode, is determined from fundamental cases, which are simply fork supported members with uniform cross-section under uniformly distributed normal force or bending moment. The standardized buckling resistance of the fundamental cases is based on theoretical and empirical background. The proposed global imperfection method is adequate for computer-aided design method using advanced elastic beam-column finite element method including the warping behavior of the cross section. The accuracy of the presented method is illustrated step-by-step with numerical examples.