The article summarizes the theoretical aspects of diagnosing the financial stability of an enterprise and emphasizes its importance for success and long-term development in a dynamic business environment. Various approaches to the interpretation of the concept of "financial stability of the enterprise" are given, influencing factors are determined. The model of diagnosing the financial stability of the enterprise as the interaction of the management subject to ensure the financial stability of the object through the use of methods, tools and levers is considered. Such methods of assessing the financial stability of the enterprise as the analysis of coefficients (the essence, calculation methodology and normative values of financial indicators) and the rating system are considered in detail. It has been proven that diagnostic methods can differ for different sizes of enterprises and branch affiliation.