A near method for the dynamic analysis of mistuned bladed disks is presented. The method is based on exact calculation of the response of a mistimed system using response levels for the tuned assembly togeher with a modification matrix constructed from the frequency response function (FRF) matrix of the tamed system and a matrix describing the mistuning. The train advantages of the method are its efficiency and accuracy, which allow the use of large finite element models of practical bladed disk assemblies in parametric studies of mistuning effects on vibration amplitudes. A new method of calculating the FRF matrix of the tuned system using a sector model is also developed so as to improve the efficiency of the method even further, making the proposed method a very attractive tool for mistuning steadies. various numerical aspects of the proposed method are addressed and its accuracy and efficiency are demonstrated using representative test cases.