INTRODUCTION: The effectiveness of the Australasian Triage System (ATS) is defined as the percentage of patients who are assessed within the ideal time frame for initiating medical examination, which is crucial for ensuring timely and appropriate healthcare in emergency hospital services. According to defined standards, the efficiency of ATS for the first triage category is 100%, for the second category 80%, for the third category 75%, while the fourth and fifth categories have a target efficiency of 70%. This classification allows for the prioritization of patients according to the urgency of their medical condition, ensuring that those in need of the most urgent care are treated without delay. OBJECTIVE: The main objective of this study was to assess the effectiveness of ATS in the Emergency Department (OHBP) of the Clinical Hospital Center Rijeka during 2023. Specific goals included evaluating the percentage of patients examined within the designated time frames for each triage category, analyzing hospital admissions, discharges, mortality rates, and identifying the mode of arrival of patients to the OHBP. METHODS AND MATERIALS: In order to collect data and achieve the research objectives, a detailed analysis of documentation was conducted, utilizing the "BIS" program – the hospital information system of the Clinical Hospital Center Rijeka. The main focus of the analysis was on gathering data on hospital admissions, discharges, mortality outcomes, the effectiveness of the ATS triage process, and the analysis of the patients' mode of arrival to the OHBP. The data were statistically processed to obtain a clear picture of the efficiency of triage and the flow of patients through the system. RESULTS: The analysis results support the main hypothesis of the study, suggesting that the ATS efficiency in the OHBP is satisfactory. Most patients were examined within the expected time frames for all triage categories. The largest proportion of hospitalized patients belonged to the third triage category (48.4%), and the majority of discharged patients were also from the third triage category (44.3%). Mortality rates among patients by triage category showed that the majority of deceased patients were from the first triage category (74.6%), which aligns with expectations given the severity of their conditions. The analysis of the mode of arrival revealed that most patients (94.9%) arrived without a referral, while 4.9% of patients came with a referral. CONCLUSION: The results of this study indicate that the ATS is highly effective in assessing the urgency of patients' conditions in the OHBP of the Clinical Hospital Center Rijeka. The system allows for appropriate prioritization of patients based on their clinical condition, ensuring timely medical care for those in most need. The ATS has proven to be a key tool for optimizing hospital resources and providing emergency healthcare, contributing to improved treatment outcomes.