Abstract : A stochastic reduced-order modelling technique for multi-stage mistuned bladed disks assemblies is proposed. In a perturbation framework, the base-line reduced-order model is built using multi-stage cyclic symmetry modelling approach. Uncertainties are introduced in the modal space at the component level and further propagated in the global modal space. This results in a compact model suitable for statistical analyses based on Monte-Carlo simulations. Applications highlight the numerically efficiency of the proposed approach which features good correlation and convergence both from deterministic and probabilistic points of view. Statistical investigations on the forced response amplification show effects of multi-stage coupling on mistuning sensitivity.