Hyssopus officinalis ssp. aristatus is the unique taxon of genus Hyssopus, wild growing in Bulgaria. It has limited distribution and a special statute - subspecies with restricted regime of use. This plant is used in the folk medicine as a cough drug and as a spice. The possibilities for application in pharmacy or perfumery are not studied yet.

The main aim of our study was to make a resource characteristic of the hyssop in South West Bulgaria and to find a promising population for introduction.

The mapping of the populations and the characterisation of resources was carried out according to "Metodika opredelenija zapasov lekartvenih rastenii" (1986). The essential oil content was determined by hydrodistillation of air-dried samples using a Clevenger's apparatus.

Eight hyssop populations were mapped and the impact of the anthropogenic pressure was accounted. The biological reserves of the studied 4 populations were very low (20-120 kg). We consider that harvesting is not feasible and desirable (economically as well as ecologically).

A promising population from Golo bardo mountain with essential oil content - 1.41% is recommended for introduction.