The article discusses the benefits and barriers associated with the implementation of integrated management systems. The results of a questionnaire survey conducted in Slovak and Ukrainian companies with implemented IMS confirm that Ukrainian and Slovak companies generally perceive the introduction of IMS positively, regardless of the length of the period (number of years) IMS is implemented. The most frequently reported benefits were (1) increased quality of products and services, (2) a competitive, and (3) customer acquisition and retention. With regard to barriers perceived, Ukrainian companies generally perceive the introduction of IMS positively, although slightly larger barriers were overcome by larger companies, the opposite was true for Slovak companies. However, the dependence of the perception of barriers in the IMS implementation on the size of the company was not statistically proven. The most frequently reported barriers were an administrative burden and a lack of tools for IMS auditing and evaluation. The study expands the empirical evidence on perceived benefits and barriers of IMS implementation and can serve managers in their effort to overcome the difficulties and take full advantage of IMS implementation.