Introduction: Identification of high-risk patients in SARS-COV-2 infection and prompt initiation of treatment are essential to reducemortality rate. In our study, it was aimed to evaluate the clinical and laboratory characteristics of patients with a diagnosis of COVID 19 who were hospitalized in our hospital and the factors that determine the severity of the disease. Materials and Methods: The files of definite/probable COVID-19 patients over the age of 18 who were followed by the InfectiousDiseases Clinic of our hospital between March 15 and November 1, 2020 were evaluated retrospectively. Results: A total of 302 patients were included in the study, 50.3% of the patients were males. Mean age of the patients participating inthe study was 62.11 ± 17.15 years. 51.3% of the patients are 65 years or older. The most common comorbidities in our patients werehypertension and diabetes mellitus. It was determined that lymphocyte count was below 800 in 22.5% of the patients. Involvementwas detected on thorax CT in 88.7% of the patients, ground glass was observed in 95.8%. The most commonly used antiviral treatmentin patients was favipiravir with 59.6%. Severe disease was present in 25.8% of all patients. In elderly patients with high comorbidities,COVID-19 was more severe, lymphopenia, hypofibrinogenemia and hypoproteinemia were more common in these patients, and therewere significant differences in AST, D-dimer, ferritin, LDH, CRP, procalcitonin, troponin, PTZ and INR values in relation to the severityof the disease. Consolidation, infiltration and atelectasis in thorax CT were significantly higher in patients with severe disease. Theaverage hospitalization period of the patients was 10.06 ± 6.07 days, the rate of follow-up in the intensive care unit was 12.6%, and5% of the patients died. Conclusion: Good identification of demographic, clinical and laboratory prognostic factors for severe COVID-19 may contribute tophysicians in the follow-up and treatment of the disease.