BACKGROUND: The antiviral agent favipiravir is an RNA-dependent RNA polymerase (RdRp) inhibitor. MATERIALS AND METHODS: We examined patients with a clinical, laboratory, and radiological diagnosis of severe coronavirus disease 2019 (COVID-19) pneumonia. We investigated the effect of administering enteral favipiravir at a 2 x 1,600 mg loading dose and 2 x 600 mg maintenance dose for 5 days in addition to the standard COVID-19 treatment. RESULTS: In total, 180 patients, who were hospitalized at the Istanbul Tuzla State Hospital and received favipiravir treatment between March 20, 2020 and May 30, 2020, were examined. Of these, 47 patients died. Thirty-three of the patients who died were aged over 65 years (70%), indicating that fatality was higher in elderly patients. Most of those who died had at least one comorbidity. Of the 101 patients who initiated favipiravir within </=3 days of hospitalization, 17 died (17%). Of the 79 patients who initiated favipiravir after >3 days of hospitalization, 30 died (38%) (P = 0.002). CONCLUSION: We found that initiation of favipiravir within the first 72 h after the onset of disease symptoms reduced fatality in patients with COVID-19.