Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 21 3 2022 06 18 241 253 Sussan Ardestani Department of Immunology, Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran Mohammad Reza Salehi Department of Infectious Diseases, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Bahareh Attaran Department of Microbiology, Faculty of Biological Sciences, Alzahra University, Tehran, Iran Seyed Mahmoud Hashemi Department of Immunology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran Somayeh Sadeghi Department of Immunology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran Sara Ghaffarpour Immunoregulation Research Center, Shahed University, Tehran, Iran Fatemeh Tuserkani Immunoregulation Research Center, Shahed University, Tehran, Iran Tooba Ghazanfari Immunoregulation Research Center, Shahed University, Tehran, Iran 2021 08 22 2022 01 15 Inflammation is an essential contributor to Coronavirus disease 2019 (COVID-19).   In this regard, finding a prognostic indicator is valuable because the treatment will be more effective if critical patients with high inflammation are diagnosed earlier. We aimed to evaluate some hematologic markers for COVID-19 and assess their association with the severity of the disease. A total of 154 COVID-19 patients were laboratory-confirmed and admitted to Imam Khomeini Hospital Complex, Tehran, Iran, from February 12, 2020, to April 4, 2020, and 55 healthy individuals were enrolled in the study. The severity of the patients' illnesses was classified into three subgroups according to the types of oxygen therapies (moderate (61), severe (28), and critical (43)) and examined the different ratios of total white blood cell (WBC) count, neutrophil to lymphocyte ratio (NLR), platelet to monocyte ratio (PLR), macrophage to lymphocyte ratio (MLR), derived NLR ratio (dNLR), and some biochemical tests. COVID-19 patients had higher levels of NLR, MLR, PLR, and dNLR than healthy subjects. receiver operating characteristic (ROC) analysis of the curve revealed that NLR and dNLR had a high diagnostic value to differentiate COVID-19 patients from healthy subjects (area under the curve [AUC]=0.923 and 0.910, respectively) and predict mortality (AUC=0.726 and 0.735, respectively). NLR and dNLR may be reliable markers to evaluate the severity of COVID-19. NLR and dNLR had a high diagnostic value for differentiating COVID-19 patients from healthy subjects, and they could predict the severity and outcome of the disease. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/3335 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/3335/1851