The SARS-CoV-2 can cause severe pneumonia and highly impact general health. We aimed to investigate different clinical features and CT scan findings of patients with COVID-19 based on disease severity to have a better understanding of this disease. For this purpose, 90 patients with coronavirus were examined retrospectively, which were divided into three categories based on the severity of the disease: mild/moderate, severe, and very severe. It has been shown that mean age and duration of hospitalization of patients increased with increasing the severity of disease. The most common clinical symptoms were shortness of breath, cough, and fever. As the severity of the disease increased from mild/moderate to very severe, there was an increase in neutrophile counts and a decrease in lymphocytes and white blood cells (WBC) showing excessive inflammation associated with severe forms of COVID-19. Subpleural changes (81%) and ground-glass opacification/opacity (GGO) lesions (73%) of the lung were the most common features among CT images of COVID-19 patients, and interlobular septal thickening (10%) was the lowest CT feature among patients. Regarding the affected parts of the lung in COVID-19 patients, bilaterial, peripheral and multiple lesions had the highest prevalence. Overall, it has been shown that clinical, laboratory and CT scan findings vary in COVID-19 patients based on disease severity, which need to be considered carefully in early diagnosis and treatment of this illness.