This article aims to evaluate the flow of patients within an Emergency Care Unit (UPA) located in State of Sao Paulo, Brazil. Patients are classified according to the degree of risk and the medical specialties of care. An analysis entitled the patients timeline was performed, which considers from the arrival to the departure of patients (length of stay), involving all the processes that occur during their stay at the UPA. Data were collected during the entire month of February 2021. A modeling was developed using the Knime software. The results showed that 383 patients were attended, 222 classified as green (less urgent), 110 yellow (urgent), 28 orange (very urgent), 12 blue (non-urgent) and 11 red (emergency). In total, 263 attended were at the medical clinic, 83 by orthopedics, 36 by pediatrics and 1 other service. The average medical attendance time in the office was 5 minutes and the average patient length of stay was 274 minutes. Considering that cases classified as red/urgent are a priority, we found that the average waiting time for triage was 9.70 minutes, above the recommendation of the Ministry of Health, which recommends immediate care. Our conclusion is that, for triage, all patients are in the same queue, and risk classification occurs after this process. Thus, it is important to note the possibility of reducing the waiting time for triage, especially for the most severe cases, since these times were longer than the patient care at the medical attendance office. Copyright (C) 2022 The Authors.