Introduction: The COVID-19 pandemic has shown that patients should be categorized according to their risk group, patient follow-up and the use of health resources should be arranged according to this categorization. Therefore, practical and inexpensive biomarkers are needed. In this study, the relationship between neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), mean platelet volume (MPV) and red blood cell distribution width (RDW) levels, which can be easily calculated by complete blood count, with mortality and intensive care unit (ICU) admission in COVID-19 disease was evaluated. Material and Method: 748 inpatients with positive COVID-19 PCR test were evaluated retrospectively. The NLR, PLR, MPV and RDW levels calculated from the complete blood count parameters of the patients at hospital admissions and their relationship with the mortality and the ICU admission in COVID-19 disease were evaluated. Results: In terms of mortality, a statistically significant difference was found between RDW levels in the evaluation performed in the patient groups who survived and died (p: 0.014). No statistically significant difference was found in NLR, PLR and MPV levels. In the evaluation performed in the patient groups who were and were not referred to the intensive care unit, a statistically significant difference was found between the two groups in RDW and NLR levels (p: 0.042, p: 0.01, respectively). There was no statistically significant difference between PLR and MPV levels for ICU admission. Conclusion: RDW level was found to be associated with COVID-19 related mortality and ICU admission.