Introduction In Republic of Moldova,the hyssopwas introducedin culturein the70-80 years of the XX-th century. In our region, the hyssop iscultivated especially for obtainingessential oilfromfreshly harvestedplants. Actually, inthe Republic of Moldovathe hyssopoccupiesof approx200ha (1).Proceeding from thefact thatthe producersincrease theareas occupied bythe hyssop,the need has arisenof determiningthe optimalharvestperiod,the correlation ofmorphological elementsin the raw material, the content and the volatile oil production, including the share of morphological elements of the harvest in the production of standard volatile oil.   Material and methods the researches atInstitute of Genetics, PhysiologyandPlant Protection of ASM on ordinarychernozemsoil wereperformed. The samples fordetermination ofbiomassaccumulationdynamicswere harvestedmanually. Volatile oil content in the raw material according to Ginsberg’ micromethod was determined (2).   Results and discussions the highest productionof hyssop raw materialis in the seed formationstage it was found. The morphological elements which constitute the hyssop harvest are the leaves, annualshootsandinfl orescences. Inbudsphase the main components of the harvest are the leavesand annual shoots,their sharebeing44.3and47.6% respectively. Fromstagetostage,the share ofthetotal organs masschange and during fl oweringperiodthe componentsratiois1:1:1. Aswas mentioned, the bestproductionof raw materialisduringseed formation, and is19,14t/ ha(Table).  Table Values components of raw materialshyssop production Indices Total,average sample Including the organs leaves annual shots infl orescences Yield, t /ha 19,14 5,14 6,97 7,03 Volatile oil content, % 0,304 0,211 - 0,468 Essential oil production, kg/ha 58,2 10,8 - 32,9 The share ofthe leavesofthe crop is5, 14t/ha or26.9% of the annual shoots6,97t/ ha or36,4% and of theinfl orescences7,03t/ha or36,7% of the total weight. Volatileoil contentin the sampleaverage is0,304%, 0,211% in the leaves, in theinfl orescences0,468% but annualshootscontainonly tracesof volatile oil. Essentialoilof the leavesproductionisequal to10,8kg/ha, from theinfl orescences–32,9 kg/ha. So,for the production ofthe hyssop essential oiloptimal harvestperiodwillbe wheninfl orescencesshareinthe total massis the biggestbecauseandvolatile oil contentishighestininfl orescences. Conclusions 1. The optimal period of hyssop harvestfor the essential oilproduction isseed formationphase. 2. Thehyssop annualshootsdoesn’t containessential oil,that is why their share inthe essential oilproductionconstitutezero has been established. 3. Atinfl orescencesof the essential oilcontentisfrom0,468% and only 0,211% in theleaves,the productionof essential oilfrom leaves andinfl orescencesis 10,2and 32,9kg /ha, respectively. 4. The highest shareboth inproductionof raw materials,and that of thevolatile oilbelongs to theinfl orescences has been confirmed.