Introduction: The current study aims to evaluate the relationship between C-reactive protein (CRP) levels, thorax CT findings and CT-SS in patients presenting to the emergency department with COVID-19. Methods: Patients diagnosed with COVID-19 by nasopharyngeal rt-PCR (+) in the emergency department were included in the study. In addition to the CRP, ferritin and D-dimer examinations of patients at admission, thorax CT involvement findings and CT-SS results were recorded. The relationship of CRP value with CT-SS and clinical outcome was evaluated. Results: A total of 974 COVID-19 patients, 572 males (58.7%) and 402 females (41.3%), with a mean age of 59.64±17.34 years, were included in the study. The CRP values of the patients who needed intensive care and needed respiratory support were also significantly higher at admission (95.1 mg/dL vs. 31.05 mg/dL) (p<0.001). The CRP values of the patients who developed any complications during the treatment of COVID-19 were higher (79.9 mg/dL vs. 41.85 mg/dL) (p<0.001). In the case of CRP >124.5, a thorax CT density score 7.35 times higher was determined to be severe. In addition, it was determined that there was a 9.09-fold increase in the incidence of negative imaging findings in terms of COVID-19 in cases where the CRP value was <12.5 mg/dL. Conclusion: The CRP levels of COVID-19 patients measured upon admission to the emergency room are correlated with the severity of lung involvement and are an important predictor of clinical outcomes.