Notion “Parameters of synchronous machines” generally means inductive reactance of these machines (or in some cases of inductance) in different operating conditions. In turn these modes can be divided into three groups - symmetric stationary, transient (or non-stationary) and asymmetrical condition. In this work the basic statements and the methodological aspects connected with inductive resistance of synchronous motor as input and use of this physical quantity are considered. Different approaches and methods of definition of these resistances are described and analyzed.