Equations for the elasto-plastic large deflection non-axisymmetric response of discretely stiffened circular plates are presented. Plastic strains within the plate and stiffener are modelled using the Ilyushin full-section and modified Von Mises yield criteria and the associated flow rule. The equations are discretised using finite differences for solution by the DR iterative procedure. The analysis is used to study the large deflection response of uniformly loaded plates stiffened by a diametral stiffener of rectangular cross-section. Dimensionless graphs of centre deflection, etc., versus pressure are presented for stocky and slender simply supported and clamped plates with shallow and deep stiffeners. (C) 2008 Elsevier Ltd. All rights reserved.