In today's competitive market characterized by hyper-competition, manufacturing organizations are rapidly evolving in accordance with the paradigm of continuous quality improvement. Continuous thinking about quality improvement imposes the need to adopt quality improvement concepts that provide long-term benefits to companies in terms of higher quality levels, overall operational performance and market leadership. One of the more popular concepts is that of lean production, which, in addition to manufacturing companies, can also be successfully implemented in service companies. The fundamental goal of implementation for all types of companies is the same - to maximize value for the customer with minimal waste, that is, "production/delivery of more with less". The transition from an old way of thinking to a lean way of thinking is a challenge for most companies. In order to facilitate implementation, practitioners and researchers have proposed a number of key success factors whose identification and ranking are necessary for the successful integration of lean manufacturing into the enterprise. However, despite the broad consensus on what needs to be done, businesses still struggle with implementation, and the advice is not universal, but situation-specific. In the literature, there is a division into internal and external. Internal ones represent those on which the company has an influence, while it does not have any external ones and must adapt to them. The identification and analysis of key factors and the elimination of inefficient processes related to the identified factors can improve productivity and ultimately stimulate the growth of manufacturing companies. Also, the implementation of lean production can be key to achieving a favorable position in international markets as well, in addition to the domestic one. In some Croatian companies, the introduction of the principles of lean production followed the emergence of the need to increase competitiveness, reduce production costs, modernize production and combat unproductivity, but lean principles are still unknown to others, the majority of Croatian companies.