BACKGROUND: In 2015, the laboratory at the Ebola treatment center in Coyah, Guinea, confirmed Ebola virus disease (EVD) in 286 patients. Cycle threshold (Ct) in the Ebola virus RT-PCR and 13 blood chemistry parameters were measured on admission and during hospitalization. Favipiravir treatment was offered to EVD patients on compassionate use basis. METHODS: To reduce biases in the raw field data, we carefully selected 163 of the 286 EVD patients for a retrospective study to assess associations between potential risk factors, alterations in blood chemistry, favipiravir treatment, and outcome. RESULTS: The case fatality rate in favipiravir-treated patients was lower than in untreated patients (31/73 [42.5%] vs. 52/90 [57.8%], p = 0.053 in univariate analysis). In the multivariate regression analysis, higher Ct value and younger age were associated with survival (p <0.001), while favipiravir treatment showed no statistically significant effect (p = 0.11). However, Kaplan-Meier analysis indicated a longer survival time in the favipiravir-treated group (p = 0.015). The study also showed characteristic changes in blood chemistry in fatal cases vs. survivors. CONCLUSIONS: Consistent with the JIKI trial, this retrospective study reveals a trend toward improved survival in favipiravir-treated patients; however, the effect was not statistically significant except for survival time.Read less <