The business world of today is full of uncertainties and its environment is extremely dynamic. One of the ways to reduce this problem is by inserting controlling in companies as an advisor and expert support to management and as a way to unburden management and take part in the responsibility that was solely management’s. Controlling’s main function is to be a business advisor and partner to management by using different tools and instruments with the purpose of achieving company’s goals. Medilab d.o.o. is a representative, importer and distributer of medical equipment and drugs of world-renowned companies. Controlling is installed in the company at the owner’s request as an answer to market demands. In addressing specific challenges, controlling and management’s cooperation is crucial. Tools and methods used are different, but the goal is the same – business success. The purpose of this thesis is to show the significance controlling has on the overall business enterprise. It endeavors to show the cooperation between management and controlling in the company Medilab d.o.o as well as the cooperation with other parts of the company. It describes the functions and tools used by controlling with the purpose of achieving the company’s objectives, coordinating and integrating single goals of different functions with the main business objective. Through operative and strategic challenges that the company is facing, the influence of controlling on business decisions and management is shown by citing concrete results that have resulted from management and controlling’s cooperation as well as the way they were accomplished. For the purposes of researching and writing this thesis different methods are used and combined, available expert literature from domestic and foreign authors, financial reports and relevant articles. Because this thesis is focused primarily on a single company, all information regarding the methods and instrument used by controlling in Medilab d.o.o. that is used in the thesis was acquired form an interview with the controller and further corresponding by e-mail.