The Hypericum L. species from the spontaneous flora of the Republic of Moldova are distinguished by the content and composition of the essential oil produced through hydrodistillation in Ginsberg’s units from the aerial part of the plant (Hyperici herba). H. perforatum L. herba contains 0.26% (dry matter) of essential oil, H. elegans - 0.15% (dry matter), H. hirsutum - 0.094% (dry matter), and H. tetrapterum - 0.13% (dry matter). GC-MS analysis of the essential oil has demonstrated substantial differences both quantitatively and qualitatively. The number of components identified in the essential oil in different Hypericum species is different. Thirty three components were identified in the essential oil isolated from H. perforatum L.,  β - caryophyllene and caryophyllene oxide at concentrations above 12% being the major components followed by  β -pinene (8.574%),  β -cadinene (4.155%), and  β -pinene (3.216%). Eighteen components were identified in the essential oil of H. elegans, g-gurjunene, aromadendrene, and undecane being the major components at concentrations of 14.532%, 13.990%, and 10.262 %, respectively. Twenty one components were identified in the essential oil of the H. tetrapterum species, copaene (9.271%) and  β -longipinene (8.489%) being the major components followed by cadinene (6.423%). Nine components were identified in the essential oil of the H. hirsutum species, elevated concentrations being found in caryophyllene oxide (10.435%), phytol (6.056%),  β - caryophyllene (5.086%) and undecane (4.279%).