This paper presents a nominal stress approach to the optimum design of structures for fatigue life requirement. The basic concept is to use the load history data, the nominal stresses of the structure and the material fatigue properties to calculate the fatigue life during the optimization process. The optimization task with fatigue life constraints and the fatigue life calculation are discussed. The life requirement is considered as side constraint and the structure weight as the objective function. The approach developed yields good results, for the design optimization of the SAE keyhole specimen, using the fatigue test data of different load histories.