Post-buckling behaviour and ultimate strength of imperfect corroded steel plates used in ships and other related marine structures are investigated. Nonlinear elastic-plastic large deflection finite element analyses are performed on corroded steel plates. General corrosion wastage is considered to be distributed randomly on either one or both surfaces of the analyzed plates. The effects of general corrosion are introduced into the finite element models using a random thickness surface model. The effects of corroded plate parameters on the plate post-buckling and ultimate strengths are evaluated in detail. It was realized that the aspect ratio and thickness (slenderness) of the corroded plates affects their strength characteristics. Age of the plate models affects mainly their post-buckling-strength regimes and degrades their buckling/ultimate strength. Also, nonlinear post-buckling characteristics of the plates suffering either one-side or both-side random corrosion exhibit some differences. Finally, simple empirical formulations are proposed in order to give rough estimations of the ultimate strength of randomly corroded plates.