Objectives: To determine the use of resources and workforce in the actual procedure time of the patient in the emergency department (ED), and to determine the total costs according to the triage levels and the factors affecting the total cost. Materials and Methods: This study is a prospective cross-sectional observational study conducted with the participation of 1,171 patients with diagnoses determined according to the frequency of presentation in the five-level triage system among 45,443 patients who applied to the ED of a tertiary hospital. The time until the clinical decision is made was determined as the actual processing time. During this period, the actual cost was measured by recording all the resources used for the patient, including workforce and the expenses of these resources, and the average per-person cost for each triage level was calculated. Results: When patients coming to the ED were grouped according to their triage levels, a statistically significant difference was found between the invoiced prices of the total patient cost for these groups. When the factors affecting the total costs were examined, it was observed that the total costs were significantly different among the triage levels. In the correlation analysis made between age and total cost, it was observed that the amount of total cost increased with increasing age. Conclusion: In multivariate analyzes, it was observed that gender, age, triage level, and type of arrival were associated with total cost. The establishment of the cost system and the implementation of effective cost management in EDs, which have a very serious income and expense cycle, are of great importance in terms of both the success of the management and the continuity of the institution or unit in hospitals. In this study, as a result of the findings revealed, it has been shown that more accurate/reliable results can be achieved by using an activity-based costing system.