Bovine herpesvirus type 5 (BoHV-5) is an etiologic agent of meningoencephalitis in cattle. The aim of this study was to evaluate the antiviral potential of a series of synthetic Mannich bases derived from lawsone and to investigate at which stage of the BoHV-5 replicative cycle the compounds might be acting. The most potent and selective inhibitor exhibited CC50 and EC50 values of 1867 μM ± 8.3 and 3.8 μM ± 1.2, respectively (ACV: 989 μM ± 2 and 166 μM ± 2, respectively).