ethanol extracts of eighteen bignoniaceae species have been evaluated by the mtt assay for cytotoxicity in vero cells and for antiviral activity against human herpes virus type 1, vaccinia virus and murine encephalomyocarditis virus. among such species, seven are reported to be of traditional medicinal use no cytotoxicity was observed for most of the extracts up to the concentration of 500 μg/ml. fourteen (50%) of the 28 extracts assayed have disclosed antiviral activity with ec50 values in the range of 4.6+0.3 to 377.2+17.7 μg/ml. only two species, arrabidaea samydoides and callichlamys latifolia, have shown activity against all the three viruses. the extracts were chemically characterized by their tlc and hplc-dad profiles. mangiferin is the major constituent of a. samydoides but the isolated compound has been less active than the crude extract. this is the first report on the antiviral evaluation of the eighteen bignoniaceae species assayed.