BACKGROUND/AIM: In this study, we aimed to evaluate the initial hematological findings analyzed on admission in confirmed COVID-19 patients who were transferred to the intensive care unit (ICU), to predict possible hematological indices. MATERIALS AND METHODS: Initial neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), monocyte to lymphocyte ratio (MLR), red cell distribution width to platelet ratio (RPR), mean platelet volume to platelet ratio, and lymphocyte multiplied by platelet count (LYM x PLT), of 695 patients with laboratory-confirmed COVID-19 were investigated and compared between the mild/moderate and severe groups. RESULTS: The proportion of COVID-19 cases admitted to ICU was 3.9%. The median age of patients admitted to ICU was significantly higher than those who were not; (68.5 (interquartile range (IQR); 21.5) years vs. 41.0 (IQR; 15.7) years; p <0.001). Severe cases had higher NLR (6.6 vs 2.4; P <0.001), and MLR (0.40 vs 0.28; P=0.004) and lower PLR (180.0 vs 129.0; P <0.001) compared to that of mild or moderate patients. Among all of the parameters, the ROC curve of NLR gave us the best ability to distinguish serious patients at an early stage (AUC = 0. 819, 95% confidence interval 0.729?0.910; p<0.001). CONCLUSION: These data showed that age, initial NLR, PLR, and LYM x PLT were associated with the severity of COVID-19 disease and patients? need for the ICU. Therefore, initial hemogram parameters may be essential to predict the prognosis of COVID-19 patients.