When structures are constructed by welding, structural members are usually accompanied by welding distortions. In this paper, the ultimate strength of transverse girders in ship structures with initial deflections under bending are investigated. First, the entire behavior, elastic-plastic large deflection, of these girders are theoretically analysed by the strip element method. A series of experiments are carried out on model girders subjected to bending moment with respect to their strong axes. Comparison is made between the test results and theoretical one and good agreement is observed between them. By these studies, a great deal of valuable information is obtained on the ultimate strength of the girders. An approximate model is also proposed to exhibit the influence of initial deflection on the ultimate strength of girders. It is found that the proposed approximate method of analysis is very useful for prediction of the ultimate strength.