The worst mistuning pattern and robust maximum mistuned forced response of a mistuned multi-stage bladed rotor are studied as an optimization problem. This approach is simulated on both a lumped parameter model of a mistuned multi-stage bladed rotor and a three-degree-of-freedom per blade disk model. Results of the optimum search of the worst-case mistuning patterns for the lumped parameter models are analyzed, which reveals that the maximum blade forced response in a mistuned bladed disk is associated with mistuning jump which causing strong localization of the vibration re-sponse in a particular blade. The three-degree-of-freedom per blade disk model is also used for calcu-lation of the maximum forced resonant response of mistuned assemblies and for determination of its sensitivity coefficients with respect to mistuning variation. Studies show that there is not a threshold of mistuning beyond which the maximum forced response levels off, or even drops, as the degree of mistuning is increased further, the tendency of the forced response maximum amplitude magnifica-tion to increase with blade mistuning. The influence of the multi-stage coupling is revealed by com-paring the results of single stage analysis with that of the multi-stage case.