The dissertation provides for a theoretical generalization and offer a solution to an important scientific and applied problem of development of conceptual, theoretical, methodological and methodical provisions for the formation of integrated management systems (IMS) of industrial enterprises, considering the impact of the complexity of the enterprise system. The study contains systematization of theoretical and methodological approaches to the definition of "integrated management system", resulting in the development of the interpretation of the concept both in a narrow (traditional approach) and broad sense. The improved concept of IMS, in contrast to the current, refers not only to a combination of several interconnected target standardized and/or nonstandardized management subsystems, which have common elements but to an enterprise management system that combines all subsystems and is constantly evolving; that ensures the efficiency, viability, competitiveness and sustainability of the enterprise in the new external and internal context of operation. The study further develops the understanding of IMS within the situational approach, which distinguishes two major stages: a) integration of standardized management subsystems into the overall management system, and b) their integration, which allows for long-term, strategic planning and management of organizational complexity to ensure the efficiency and effectiveness of the IMS. There determines theoretical and methodological approaches to assess the effectiveness of IMS under the parameters of the complexity of the enterprise system. For the first time, it is proposed to evaluate the effectiveness of IMS through the use of the concept of "complexity", which solves problems related to the implementation and practical use of IMS, which are manifested in uncontrolled growth of management complexity, which in turn reduces both its efficiency and motivation of the enterprise to use IMS in general. The application of the project approach to the formation of the IMS is substantiated and the phases of the formation of the IMS is developed. It is proved that there is a relationship between environmental factors and the introduction of standardized enterprise management systems. It is substantiated that each country has its own set of factors of the external environment of enterprises that influence their decision to implement standardized management systems. It is determined that there exist similar models of the external environment of enterprises, which stimulate the introduction of standardized enterprise management systems. It was found that in Ukraine none of the selected environmental factors showed a correlation with the process of implementation of standardized enterprise management systems. In our opinion, this indicates that in general enterprises in the country do not consider the trends of changes in the external environment while forming IMS, which negatively affects their development. However, companies that are focused on the external markets, in particular, the EU market, implement standardized targeted management systems to modernize their business processes. It is proved that the introduction of standardized management subsystems with their subsequent integration increases the complexity of not only the enterprise management system but also the managed subsystem. Therefore, the impact of the IMS or its non-integrated components should be assessed on the scale of the entire enterprise system, and the assessment of the level of complexity should take into account all elements of the enterprise system. It is determined that enterprises that have already integrated standardized control subsystems have a smaller increase in complexity than enterprises that have implemented autonomously operating (non-integrated) standardized control subsystems. It is substantiated that the formation of IMS causes an uneven increase in the complexity of the elements of the enterprise system. The indicators of the domestic market of the checkpoint, in particular production volumes, sales, export, import volumes in dynamics of past years are analysed. The degree of prevalence of certified (sub) control systems at the enterprises-manufacturers of checkpoints is scrutinised. It was found that the most common of those used is DSTU ISO 9001: 2015 "Quality Management Systems". There is a low level of interest in the implementation of DSTU OHSAS 18001: 2010 "Occupational Health and Safety Management Systems". Only two companies, which are leaders in the domestic market of cable products, have integrated standardized management systems. A method has been developed to identify the links between the complexity of the MIS, the complexity of the managed subsystem and the financial results of the enterprise. There is also proposed a method for selecting IMS strategies to
