Controlling is a function and subsystem of management that helps management when defining goals, planning, controlling, measuring performance, informing, managing human resources, etc. In a challenging business environment, the controller relieves managers by ensuring the transparency of results and information that will alert managers to deviations from the plan and direct it toward the goal. By using controlling, management knows where it is, what it wants to achieve, and how to achieve it. This thesis analyzes the characteristics, quality, and sustainability of the healthcare system of the Republic of Croatia and makes a brief comparison of the application of controlling in other countries compared to Croatia. The introduction of controlling in the healthcare system improves the management function and increases the efficiency of the entire healthcare system. Precisely because the issue of the health system is one of the fundamental issues of every modern state, it is essential to provide good strategic and operational control instruments to deliver all relevant information on the budget and reports on medical services promptly. Also, the implementation of the information system itself is of great importance to properly introduce control and monitor quality. This topic is extremely important for the Republic of Croatia due to the fact that doctors or other medical personnel mostly participate in the operational management of the Croatian healthcare system. It is possible that this group of stakeholders is not qualified for such management and managerial knowledge and skills, so there is still a lot of room for quality improvement in this area. In conclusion, the goal of this paper is to point out the importance of controlling and management in the healthcare system of the Republic of Croatia, because by using key parameters it is possible to monitor the evaluation process, turn weaknesses into strengths, and build a good business core essential for a sustainable healthcare system.