Objective: To investigate the effect of the use of color codes for patient triage on physicians\' clinical decision. Methods: This prospective study was conducted among female patients aged 18-65 years who visited the emergency department (ED) with complaints of acute abdominal pain. A 3-level of triage system [red (very urgent), yellow (urgent) and green (less urgent)] was used in our ED. All patients were green level. Half of these patients remained at the green level (the green group), and the remaining patients were re-labeled as false yellow (the false yellow group) in the order of ED visits. Ordering tests, consultation requests, intravenous treatment, length of hospital stay, and cost were compared between the two groups of patients. Results: In total 393 patients were included with 198 patients in the green group and 195 in the false yellow group. There was no statistically significant difference between the two groups in age, temperature, systolic blood pressure, diastolic blood pressure, pulse and oxygen saturation (P>0.05). It was observed that more tests (P=0.001), consultations (P<0.001), and intravenous treatment were requested (P<0.001), and the duration of stay in the ED was longer (P<0.001) and cost (P<0.001) was higher in the false yellow group. Conclusions: Triage do affect the decisions of physicians on female patients with acute abdominal pain.