Introduction: Early detection of the severity of COVID-19 disease is important for patient prognosis and effective use of hospital capac- ity. Early detection of critical patients and providing supportive treatment is the main goal of disease management. In this study, we evaluated demographic, clinical, laboratory and radiological findings in COVID-19 patients and aimed to find risk factors associated with poor prognosis. Materials and Methods: A total of 579 cases hospitalized with the diagnosis of COVID-19 were evaluated retrospectively. The diagnosis of COVID-19 was confirmed by polymerase chain reaction (PCR) positivity or typical clinical, laboratory and radiological findings. The study population was divided into groups according to the World Health Organization (WHO) COVID-19 disease severity classification. Significant risk factors associated with severe disease and mortality were investigated by comparing the demographic, clinical, labora- tory and radiological data of these groups. Results: Mean age of the 579 cases was 54 +/- 18.25, and 321 of them (55.4%) were male. Severe disease was detected in 131 (22.6%) patients and mortality rate was %8.29. The most common comorbidities were hypertension (31.8%), diabetes mellitus (18.5%) and coronary artery disease (17.8%), respectively. The most common symptoms at the time of admission to the hospital were cough (40.7%), fever (38 degrees C;33.6%) and shortness of breath (26.3%). Age, coronary artery disease and shortness of breath, neutrophil count, urea, CRP, ferritin, Pro-BNP, fibronogen, IL-6 values were found to be predictive variables for severe disease. Age, presence of shortness of breath, urea, ferritin and Pro-BNP values were found to be independent predictive variables for severe disease, and the cut-off points were calculated for these variables (age 59.5, urea 33.5 mg/dL, ferritin 50.8 mu g/L and Pro-BNP 881 pg/mL). Conclusion: Some predictive factors were demonstrated to detect severe disease in COVID-19 patients. It is important to predict poor prognosis based on these factors. It provides early detection of critical patients and it will be a guide for reducing mortality rates in these patients with effective treatment.