Orthogonal stiffened plates present in the ship deck are subjected to axial compression due to hogging and sagging bending moments and, lateral load due to cargo load. The main objective of this investigation is to determine the ultimate load carrying capacity and study the interactive behaviour of orthogonal stiffened plates under axial and lateral loads. Tests were conducted on six stiffened plates with plate slenderness ratios of 80 and 64, and corresponding column slenderness ratios of 24 and 26. Hydraulic jacks and inflatable air balloon with load control mechanism were fabricated to apply axial and lateral loads on the test specimens respectively. All the specimens were tested up to ultimate load and the mode of failure was determined based on the initial yielding observed in the plate and/or stiffener. Nonlinear finite element analysis of test specimens was performed using the general purpose FE software ANSYS®. Both material and geometric nonlinearities were considered in the FE analysis of test specimens. The ultimate loads obtained from the finite element analysis were compared with experimental data and found to be satisfactory. It was also observed that the mode of failure obtained from finite element analysis is similar as observed from experiments. It was concluded that the increase in lateral load beyond two thirds of ultimate lateral load significantly reduces the axial ultimate load carrying capacity of stiffened panels. The interactive effect of stiffened plates subjected to combined action of axial and lateral loads is determined as nonlinear. © 2010 Korean Society of Civil Engineers and Springer-Verlag Berlin Heidelberg.