OBJECTIVE: This study investigates whether C-reactive protein, platelet-lymphocyte ratio, and neutrophil-lymphocyte ratio could be useful to predict mortality in COVID-19.METHODS: Data of 635 patients with COVID-19 followed up in Sinop Ataturk State Hospital from February to May 2020 were evaluated retrospectively. Diagnosis of COVID-19 was made according to the interim guidance of the World Health Organization. Patients were grouped into two groups based on mortality as survived and non-survived patients. Age, gender, neutrophil-lymphocyte ratio, plateletlymphocyte ratio, and C-reactive protein of the groups were investigated and compared. RESULTS:The mean age of the participants was 55.8±22.3 years. Among the patients, 584 survived and 51 patients died. Age was significantly different between the groups, 54.2±22.3 in the survived group and 75.6±11.1 in the dead group (p=0.000). In addition, neutrophil, C-reactive protein, and neutrophil-lymphocyte ratio values were significantly higher in the dead group (p=0.000). plateletlymphocyte ratio was slightly higher in the dead group, but this difference was not significant (p=0.42). The area under the curve values for age, lymphocyte, platelet, C-reactive protein, and neutrophil-lymphocyte ratio are 0.797, 0.424, 0.485, 0.778, and 0.729, respectively. CONCLUSIONS: Our results showed that neutrophil-lymphocyte ratio and C-reactive protein are significantly higher in patients leading to death and could be effective biomarkers in predicting COVID-19 fatality. Furthermore, C-reactive protein could be used as an independent biomarker to predict death in patients with COVID-19, regardless of gender and age (p=0.000).