Background: Sepsis is a significant contributor of mortality all over the world. Emergency departments have a critical role for diagnosing a suspected sepsis in a patient, since early and proper administration of antibiotics may decrease mortality significantly. But, the unavailability of an objective and reliable diagnostic test is the major challenge of this critical issue. Aims: The aim of this study is to evaluate the prognostic value of a novel biomarker, the ischemia-modified albumin (IMA) in patients with sepsis and septic shock in emergency department. Subjects and Methods: This prospective, observational study included 81 patients with sepsis or septic shock and 75 controls. Sociodemographic characteristics of the patients, site of infection, IMA levels, other biomarkers (procalcitonin, pH, lactate), mortality at 24-h and 28-day were evaluated. Results: The serum IMA levels in patient and control groups were 117.8 +/- 85 IU/g and 115.8 +/- 134.0 IU/g, respectively (P = 0.072). There was a weak but statistically significant positive correlation between IMA and lactate levels (P = 0.009). The mortality rates of patient group at 24-h and 28 days were 21% and 79%, respectively, but serum IMA levels were not found to be a prognostic marker to predict mortality. Conclusion: The main reason for the similarity between groups regarding IMA levels was thought to be associated with the distribution of the acute and chronic health problems other than sepsis in the control group. Emergency department physicians should not only depend on serum IMA levels for predicting the prognosis of patients with sepsis or septic shock.