A method of inelastic buckling analysis of thin-walled sections is described. The method is based on the semi-analytical finite strip method of structural analysis. Deformation and flow theories of plasticity are included to take into account the nonlinear stress-strain relationship of the material. Strain hardening and residual stresses are also included in the analysis. The method of inelastic buckling analysis is applied to various cold-formed sections and hot-rolled sections. The results are compared with theoretical values and test results.