Clinical quality indicators evaluates the quality of work in healthcare institutions. Each organizational unit of a hospital system must have elaborated procedures and documented measurements to analyze and improve the work process. One clinical indicator of quality is operating room utilization, which is presented as a percentage over a period of time. The first objective of this research is to calculate the utilization rate of elective operating rooms on Surgery Clinic in Cinical Hospital Center Rijeka, for the period of two months, September and October 2019. The second aim of this paper is to investigate the factors that influence on utilization rate, to compare the results obtained with the results found in the literature, to point out possible problems, and to try to find effective solutions. After obtaining the consent of the Ethics Committee of Clinical Hospital Center Rijeka, a retrospective study was carried out using data taken from the hospital information system of Clinical Hospital Center Rijeka for September and October 2019, as well as data from the operating protocol and operating program. In September and October 53,359 minutes were worked out from a total of 82,560 minutes, which amounts to a total of 64.63% of the utilization, while the adjusted utilization with a change time amounts to a total of 64.573 minutes or 78, 21%. During that period, unused time before the first patient entered the room was 9.574 minutes (11.60%), and unused time after the last patient left the room was 8723 minutes (10.56%). Operating room utilization can be improved by introducing new guidelines to accelerate patient flow, better communication and teamwork.