Objective:The aim of this study was to explore association of initial laboratory parameters of hospitalized patients with COVID-19, with the severity and death incident. Methods: In this retrospective study, patients were classified based on mortality outcome (survivor and non-survivor) and disease severity (non-severe, severe, and critical). The initial laboratory data (within the first two days of hospital admission) were compared between these categories. Results: Of 362 COVID-19 patients hospitalized between January-2021 and May-2021, 39.0% were non-severe, 32.2% severe, and 28.7% critical. 77.3% were lived and 22.7% died in hospital. Non-survivors were significantly older than survivors. There was a statistically significant association between exceeding the cut-points of laboratory parameters and the severity of the disease or even death. These laboratory parameters included D-dimer, C-reactive protein, prothrombin time, ferritin, white blood cells, neutrophil count, aspartate aminotransferase, creatinine, blood urea nitrogen, lymphocyte count, and albumin. Also, exceeding the cut-points of these parameters showed high odds of death. The highest odds ratio was reported for albumin <3.5 g/ dL (OR=14. 318 [4.784-42.851], p<0.001). Conclusion: The cut-points of the laboratory parameters could effectively be used as predictors to assess the severity and risk of death to improve the management of COVID-19 patients.