ABSTRACT Aim The aim of the study is to investigate the relationship between negative acute-phase reactants and positive acute-phase reactants with in-hospital mortality in patients diagnosed with acute ischemic stroke (AIS) in the emergency department (ED). Methods and Materials Patients aged 18 and older who presented to the ED of a tertiary hospital with AIS were included in the study. Demographic and clinical characteristics, laboratory parameters, acute-phase reactants, National Institutes of Health Stroke Scale (NIHSS), and outcome data of the included patients were recorded on a standard data form. Results A total of 588 patients were included in the study. When the in-hospital mortality of patients was examined, the mortality rate was 17.7%. In the analysis for predicting mortality, it was determined that albumin had the highest predictive power between the area under the curve (AUC) and the determined predictive values (AUC: 0.759, 95% CI 0.707–0.810, p < 0.001). The analyses of the study data revealed that albumin (<0.001) and TF (p = 0.049), which are negative acute-phase reactants, were independent predictors of mortality. According to our study data, in patients with AIS, for each unit decrease in albumin level at the time of ED admission, the risk of mortality increased by 0.868 times, and for each unit decrease in TF level, the risk of mortality increased by 0.593 times. Conclusion According to the study data, albumin and TF levels, which are negative acute-phase reactants, are independent determinants of in-hospital mortality in patients with acute ischemic stroke in the emergency department.