Aim: It has been reported that the increased neutrophil/lymphocyte ratio (NLR) is associated with a poor prognosis in Coronavirus disease-2019 (COVID-19) patients. We aimed to correlate three consecutive computed tomography severity score (CT-SS) values with simultaneous NLR and other laboratory parameters and investigate their temporal changes effects on the prognosis of COVID-19 patients. Methods: This single-center cross-sectional study included 99 (aged ≥18 years) COVID-19 patients hospitalized between March 1, 2021, and June 30, 2021. Demographic data, laboratory findings, and intensive care unit (ICU) admissions were obtained from electronic medical records. We divided patients into two groups: ICU and non-ICU patients A radiologist calculated three consecutive chest CT-SSs using a 25-point visually semiquantitative system. Spearman’s rho correlation was used to evaluate correlations between CT-SSs and laboratory parameters in ICU and non-ICU patients. Results: The study population included 99 patients with a mean age of 61.17±14.36 years. Significant associations were found between the third-highest values of CRP (p=0.005), D-dimer (p=0.007), lactate dehydrogenase (p=0.027), and ICU admission. While there was no statistical significance between the first and second CT-SS and ICU admissions, there was a significant relationship between the third CT-SS and ICU admissions (p=0.013). Moderate positive correlations between the first NLR and CT-SS (p=0.025, r=0.488) and the second NLR and CT-SS (p=0.001, r=0.650) were found in ICU patients. Conclusion: Our results demonstrate the importance of late follow-up chest CT and laboratory parameters for the prognosis and ICU admissions of COVID-19 patients.