OBJECTIVE: To investigate the association of white blood cell (WBC) counts, neutrophil, platelets, lymphocyte counts, C-reactive protein (CRP), neutrophil / lymphocyte ratio (NLR), derived NLR ratio (d-NLR), and platelet / lymphocyte ratio (PLR) at the time of first admission for mortality caused by COVID-19. STUDY DESIGN: Descritive, analytical study. PLACE AND DURATION OF STUDY: Department of Emergency Medicine, Sakarya University Training and Research Hospital, Turkey from March 2020 to May 2020. METHODOLOGY: One hundred and sixty-nine patients with the diagnosis of Covid-19 were retrospectively reviewed. Patients were divided into two groups as survivors and non-survivors. Inclusion criteria were age >/=18 years, RT-PCR test positivity, hospitalisation. Patients with missing data were excluded. Data regarding age, gender, WBC counts, neutrophil, platelets, and lymphocyte, CRP, NLR, d-NLR, PLR and comorbid conditions were analysed for mortality. All tests were done with a two-sided significance of 5%. For each endpoint, the absolute and relative effects and their corresponding 95% confidence interval were calculated. RESULTS: There was a statistically significant association between neutrophil, lymphocyte, CRP, NLR, d-NLR and PLR values (p=0.005, p<0.001, p<0.001, p<0.001, p<0.001, and p<0.001, respectively) with mortality status of the patients. The cutoff values calculated by this analysis were 67.50 years for age, 5.12 K / microl for neutrophil, 1.12 K / microl for lymphocyte, 67.78 mg / dl for CRP, 3.9 for NLR, 2.55 for d-NLR, and 148.85 for PLR. CONCLUSION: Altered neutrophil and lymphocyte counts, NLR, d-NLR, PLR, and CRP values can be used as early predictors of mortality in Covid-19 patients. Key Words: Covid-19, Mortality, Emergency, NLR, d-NLR, PLR.