The effect of imperfections on the maximum strength of isolated, simply supported biaxially bent steel H-columns is studied with the help of a computer program. The influence of the pattern and intensity of residual stresses is considered first. The effect of the sign and magnitude of initial crookedness is then examined. Finally, the variation of the influence of residual stresses and initial crookedness with slenderness is presented. It is indicated that the numerical results given and the computer program, could be used to check the validity of the existing design methods, after selecting the representative imperfections.