The aim of the present paper is to investigate the ultimate strength characteristics of plate elements with pit corrosion wastage under axial compressive loads. Collapse tests on a box column type of steel-plated structures with diOEerent degrees of pit corrosion damage are undertaken. A series of ANSYS non-linear nite element analyses for steel plate elements under axial compressive loads are carried out, varying the degree of pit corrosion intensity and plate geometric properties. In this paper, a new parameter, i.e. the smallest cross-sectional area, is proposed to represent the ultimate strength reduction characteristics due to localized corrosion. It is proved that the proposed parameterbased approach is more useful than the traditional approach based on equivalent thickness in terms of the accuracy of ultimate strength predictions of pitted plates. Closed-form design formulae for the ultimate compressive strength of pitted plates, which are needed for the ultimate limit state-based risk or reliability assessment of corroded structures, are derived by regression analysis of the experimental and numerical results obtained from the present study. The insights developed will be very useful for the damage-tolerant design of plated structures with pit corrosion damage.