In the paper the methodology in the assessment of operator activities in man-machine systems is offered. The approach offered is directed to the solution of the contradiction between the definition of qualifying requirements to operator activity in indices of its quality and existing methods ensuring the assessment of the functional efficiency of activity. The indices of the quality assessment of operator activity and charac-teristics of qualifying requirements for operators of “man-machine” systems are defined. In the paper there is shown a structural chart of a program complex for the assessment of operator activity quality. Methods of a statistical modeling suitable for the solution of the problem of accuracy increase in the assessment of operator activities quality are considered. Basic requirements and assumptions used in the course of the formation of a model of the operator activity and assessment of its quality are defined. The assessments of quality indices of operator activity obtained on the model can be specified using various procedures increasing the efficiency of statistical method modeling. A statistical modeling allows imitating the activity processes actually without limitation of the amount of factors taken into account and without demanding the presentation of inves-tigated dependences in an actual view regarding a desired variable. A variety of used in practice indices and methods of their assessment is determined first of all by a varied structure of existing kinds of operator activity and their purposefulness.