BACKGROUND: Pulmonary fibrosis can persist long after recovery from coronavirus disease 2019 (COVID-19) infection, thereby reducing quality of life and lung function. We aimed to evaluate the frequency and risk factors for pulmonary fibrosis in patients with severe COVID-19 pneumonia requiring mechanical ventilation (MV), a high-risk group for developing pulmonary fibrosis. METHODS: Clinical data and chest computed tomography (CT) scans of patients with severe COVID-19 pneumonia requiring MV were retrospectively collected from nine hospitals in South Korea. Fibrotic-like changes on chest CT were visually assessed. RESULTS: = 0.018) was associated with a reduced risk of pulmonary fibrosis, along with a higher heart rate on intensive care unit admission. CONCLUSION: Our study demonstrated that in patients with severe COVID-19 pneumonia requiring MV, chest CT revealed fibrotic-like changes in approximately three-quarters of patients. In addition, our results suggest that higher daily doses of steroids may be associated with a reduced risk of pulmonary fibrosis. Further research is needed to determine the appropriate steroid dose that may reduce the progression of pulmonary fibrosis and improve clinical outcomes. TRIAL REGISTRATION: Clinical Research Information Service Identifier: KCT0006312.