Background: FAR is being tested as a novel marker for many inflammatory diseases. Many studies have linked the high FAR level to the severity of illness and mortality. Aim: To evaluate the FAR's potential application in COVID-19 patients as a predictor of illness severity and in-hospital mortality, that may improve management of COVID-19 patients .Patients and methods: This prospective cohort study was conducted at COVID-19 Isolation Unit, Zagazig University hospitals in Egypt. WBCs, CRP, ferritin, albumin, fibrinogen, and evaluation of the fibrinogen to albumin ratio and assessment of outcome by in hospital death and length of hospital stay were done for all patients. Results: Between the first and seventh days, there was a substantial change in fibrinogen and FAR that significantly increased on 7th day while albumin significantly decreased on 7th day . Critically ill patients had FAR that was greater than moderate and severe patients, as well as severe patients than moderate patients. A mean LOS was 11.7 ± 2.9 days and 68% of them were survived. There was a sizable distinction between survivors and non-survivors in terms of fibrinogen on 7th day and FAR on 1st and 7th days that were lower in survivors compared to non-survivors. Additionally, there were differences between albumin levels in survivors and non-survivors on 1st and 7th days.The fibrinogen on 7th day, albumin 1st and 7th days, FAR 1st and 7th days could be used to predict mortality. Conclusion: In COVID-19 patients, the fibrinogen to albumin ratio could be used to predict mortality.