Fluoxazolevir (NCGC00351982) is a potent, small molecule entry inhibitor of HCV with EC50 of 18.8 nM.Fluoxazolevir inhibits fusion of HCV with hepatic cells by binding HCV envelope protein 1 (E1) to prevent fusion.Fluoxazolevir was generally effective against all chimeric HCV-RLuc genotypes including 1a, 1b, 2b, 3a, 4a, 5a, 6a and 7a, was most effective against HCV 2a and 2b, followed by 3a and 6a, all within sub-μM EC50 values, with little to no cytotoxicity (CC50>20 uM).Fluoxazolevir was highly synergistic with other anti-HCV drugs (interferon-α, ribavirin, daclatasvir, sofosbuvir and simeprevir (NS3/4A protease inhibitor)).Fluoxazolevir suppresses HCV infection in humanized chimeric mice, and is active against multidrug-resistant HCV.Fluoxazolevir also broadly blocked human coronavirus entry into various cell types, inhibit SARS-CoV S- and SARS-CoV-2 S-mediated infection MA104 cells with EC50 of 6.49 and 3.86 uM, respectively.