Antiviral activity of rybamidil (virasol) and interferon inducers ridostine and camedone developed in Russia and introduced in practical medicine has been studied in mice with experimentally induced arboviral infections, flavivirus (tick-borne encephalitis-TBE, and yellow fever-YF) and alphavirus ones (Western and Eastern equine encephalomyelitis-WEE and EEE). Rybamidil injected subcutaneously proved to be ineffective both for prevention and treatment of these infections. Early interferon inducers ridostine and camedone (larifan) with a peak of interferon production 4 hours after injection, when used in doses of 5 and 150 mg/ kg, respectively, had a clear-cut prophylactic antiviral effect if injected 24 or 4 hours before infection. Ridostine had a distinct antiviral effect, providing up to 40% protection from TBE, YF, and WEE.