Backgroundsevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or Covid-19 is a nationwide public health emergency with significant impact on human life.ObjectiveTo develop a new simple hematological prognostic index for Covid-19 severity state.Patients and methodsThis observational cross sectional study was conducted on 250 patients with Covid-19 disease. Age, gender, and severity of Covid −19 were recorded. Complete blood count and lactate dehydrogenase were measured.New index: COVID-19 severity-Iraqi-index = CSI index to predict COVID-19 severity.CSI index is monocyte/lymphocyte absolute counts multiplied by LDH (lactate dehydrogenase)/upper normal reference laboratory range of LDH value.ResultsMean age of patients was 50.4 + 15.1 years. Majority of patients were Males 148 (59.2%)..Most of patients were in stage 2 and 3 (> 94%). There was a significant difference between means of White Blood Cells, lymphocytes and Monocytes among the different stages of the disease (P = 0.0001, 0.036, 0.012). There was a significant moderate correlation between the prognostic index and the stage of the disease (r=0.41, p=0.0001).ConclusionsCSI index is a new simple predictor of clinical outcome in patients with covid-19 during early stage of the disease.