A series of novel (5-oxazolyl)phenyl amine derivatives were synthesized and their antiviral activities against the hepatitis C virus (HCV) and the coxsackie virus B3 (CVB3) and B6 (CVB6) were evaluated in vitro. Bioassays showed that the synthesized compounds 17a1, 17a4, 17a6, 17b1, 17d1, 17e2 and 17g3 exhibited potent antiviral activity against HCV (IC₅₀ = 0.28-0.92 μM) and most synthesized compounds exhibited low cytotoxicity in Huh7.5 cells, compared to telaprevir. The compounds 17a1, 17a4, 17a5, 17a6, 17b1, 17b2, 17g1 and 17g3 showed strong activity against the CVB3 and/or CVB6 at low concentrations (IC₅₀ < 2.0 μM). The (5-oxazolyl)phenyl amines 17a1, 17a4, 17a8, 17b1, 17d1, 17e2, 17f3 and 17g3 were identified as the most active on the biological assays, and will be studied further.