In this paper, the stability resistance of beam-columns with monosymmetric I-section are examined according to prEN 1993–1–1:2020 standard. The buckling behaviour of the members with monosymmetric I-section is different from doubly symmetric cross-section because the eccentricity between the shear centre and centre of gravity causes additional second-order bending moments and second-order bimoment from compression. This paper aims to show a comparison between the results of the Interaction Method, General Method and the Overall Imperfection Method. To investigate the accuracy of the above-mentioned design methods several geometrically and materially nonlinear analyses with imperfections (also known as GMNIA) were carried out by the authors. The parametric study showed that the different methods have similar safety level in the investigated cases.