Тhe article presents an author's method to monitor and assess innovative activity of enterprises in order to investigate the status and prospects of their functioning. The purpose of this monitoring is to diagnose the state of the high-tech enterprise system performance, taking into account specific features of the high-tech sector, which is especially important in the conditions of economic sanctions. The paper provides a conceptual model to monitor development of innovative enterprises, gives a method to estimate innovative potential of an enterprise, productivity and efficiency of an innovation enterprise. Effectiveness of innovative activity is interpreted by the authors as the level of the achieved positive economic effect due to innovative activity of the enterprise. According to the authors, considering the obtained ratio of the innovative potential and effectiveness of innovative development, one can conclude about the strategy of innovative development. As performance indicators of the strategy of a innovative high-tech enterprise it is proposed to consider the value added per employee or productivity, calculated on gross value added, as well as profitability of sales of high-tech products. Scientific novelty of the proposed method is that it can be used to study the dynamics and efficiency of the potential of an enterprise, to select measures to stimulate development of high-tech enterprises, to develop and realize innovative strategy and assess its efficiency. The methodology for monitoring and evaluation of innovation activities may be used by enterprises’ management teams and executive government bodies. One of the most promising areas for further research in the area of an enterprise’s innovative activity monitoring and evaluation, in our opinion, is development of tools for accounting the stage of innovation life cycle of and enterprise’s life cycle in monitoring.