The paper discusses the problem of estimating the similarity of two or more control systems. In accordance with the statements made earlier it is indicated that such management systems should be characterized by a strict or approximate equality of hte values of targeted indicators (criteria) of control effectiveness. Two main variants of procedures for estimating the control systems similarity are proposed. The first is based on the direct evaluation of the targeted indicators of control performance, the second - on the use of the so-called similarity relations, describing the conditions the fulfillment of which is valid for such systems. The procedures for evaluating the control systems similarity rerations are assotiated with considerably less expenses.