Purpose: The first goal of the article was to examine how the perception of the role and scope of operation of maintenance services in the enterprise changes, depending on whether the company has an integrated management system (IMS), only a quality management system implemented in accordance with ISO 9001 and in the absence of a formal, certified management system. The second goal was to propose a model for assessing the quality of maintenance service functioning in enterprise with IMS implemented.Design/methodology/approach: The author's experience of over 1,000 audits in enterprises in various industries: food, automotive, construction, petrochemical, electronic and so on was used in the work. The audits were carried out in three types of companies: which had IMSs (800 audits), which only had a system implementation certificate ISO 9001 (140 audits) and without any standardized management system implemented (so-called second-party audits, commissioned by the client of the audited company.Findings: The most important conclusion is – the role of UR services in enterprises with the implemented IMS is much broader and goes beyond the classic framework for planning, implementation and settlement of maintenance and repair work. Maintenance is understood more broadly and includes in its scope also the safety of people and the environment, the efficiency of production and consumption of utilities as well as the quality of products and services. Maintenance issues include not only strictly technical aspects but also economic, logistic, legal and organizational and management aspects.Practical implications: Research shows that enterprises, especially those with high technical and organizational culture, should not treat management systems as costs, but as a driving force for the implementation of new technologies, new organizational solutions and the development of employees' competences.Social implications: Broad views on stakeholders of maintenance services (including employees, their families, control institutions) and their requirements make enterprises begin to see the need to maintain the so-called lifetime balance, as well as the safety and comfort of work of employees of these services.Originality/value: The author did not find in literature any reports on studies of the impact of formal, certified management systems on the quality of maintenance services; this article shows that this impact is large and, above all, positive; with such a broad understanding of the role of maintenance, there is a need to develop a common platform for such seemingly distant concepts as machine technical condition or fatigue life versus cost accounting and quality management.