The article is devoted to the of theoretical and methodological foundations development of the research of the adaptive potential of an enterprise in terms of the application of the conceptual provisions of the system methodology and the system stability theory. The authors substantiated that the adaptation of an enterprise to modifying external and internal factors indicates the most important feature of its sustainability, a quantitative measure of the enterprise adaptive capabilities being its adaptive potential. Interpretations of the studied concept are analyzed, the authors' definition of the enterprise adaptive potential based on the application of a complementary resource-efficient approach is proposed. A methodology for assessing the enterprise adaptive potential is proposed using the main indicators of financial condition: liquidity ratios, financial stability, profitability. An assessment of the adaptive potential of Russian ferrous metallurgy companies under the conditions of the COVID-19 coronavirus pandemic was made.