Abstract In this paper the aspect of ductility in plastically designed sway frames is discussed. Regular multi-storey frameworks are considered, with the object of formulating simple semi-empirical design rules. The ductility demand on members to achieve sufficient moment redistribution for a collapse mechanism to occur has been based on simple models similar to those employed in approximate earthquake design. The ductility capacity of compact beam and column sections has been limited to prevent premature member failure due to local flange and web buckling. For practical sway frames the resulting proposals to safeguard against ductility failures appear in the format of allowable slenderness ratios. The formulations must be seen as a first-level approximation to assess the problem of ductility in multi-storey sway frames.