In this report solutions are presented for the inelastic lateral-torsional buckling strength of as-rolled steel wide-flange beam-columns. The beam-columns are subjected to an axial force and to bending moments applied either at one end of the member only or equally to both ends. The reduction in strength due to lateral-torsional buckling as compared with the in-plane performance of the member is examined and the influence of the cross-section size@ yield stress level@ and residual stress level on the lateral-torsional buckling strength is determined. The theoretical solutions are then compared with an approximate reduction formula which is proposed for design purposes. Available test results are compared with the theory as represented by this reduction formula.