colombian flora includes plant families such as labiatae and verbenaceae which are employed for treatment of several diseases. in this study, the chemical compositions of essential oils belonging to labiatae and verbenaceae families were determined by gc-ms and gc-fid, respectively. the antiviral activity of forty essential oils of these plants and some monoterpenes were evaluated on human herpes viruses types 1 and 2 using end-point titration technique (eptt). furthermore, the essential oils and monoterpenes with higher activity reported in the screening were used to evaluate the inhibitory effect on pre-infective stages. the essential oils with the most anti-herpetic activity were those of labiatae family with rf values of 1 x 102 and 1 x 103 against one tissue culture infectious dose 50 (tcid50) of hhv-1 and hhv-2. moreover lepechinia salvifolia, hyptis mutabilis, lepechinia vulcanicola, mintostachys mollis and ocimum campechianum essential oils showed inhibitory activity in the early stages of infection.