Background: Hyssopus officinalis L. (hyssop), a species native to the Caspian Sea region, has been cultivated in the Republic of Moldova as aromatic plant and has been used in folk medicine as antitussive, expectorant, carminative, digestive and sedative remedy. Material and methods: The aerial parts of H. officinalis L., with pink, white and blue flowers, were collected from the collection of the Scientific Practical Center in the Field of Medicinal Plants during flowering phase. The extracts were obtained with 70% ethanol by maceration with stirring. The concetration of the extracts was done with the rotative evaporator Laborota 4011. Identification of phenolic compounds in dried extracts from hyssop herb was carried out by thin-layer chromatography. The total content of hydrocyanamic acids was measured in plant products and dried ethanolic extracts, by spectrophotometric method, with Arnow’s reagent. Quantitative analysis of total phenolic content was carried out by UV-spectrophotometry analysis, using a Metertech UV/VIS SP 8001 spectrophotometer. Results: The chlorogenic (Rf 0.47) and caffeic (Rf 0.93) acids were identified in the three genotypes of Hyssop herba, with pink, white and blue flowers. The total of hydroxycinnamic acids, expressed in caffeic acid, for both, aerial parts and dry extract, was the highest in H. officinalis L. with white flowers (1.484 mg/g; 3.014 mg/g respectively), followed by H. officinalis L. with pink flowers (1.190 mg/g; 2.915 mg/g) and H. officinalis L. with blue flowers (1.015 mg/g; 2.851 mg/g). The highest polyphenol content, expressed in gallic acid equivalent (GAE), was found in the dry extract of H. officinalis L. with blue flowers (39.056 mgGAE/g dry extract). Conclusions: This study showed that the extract of the Hyssopus officinalis L. containing phenolic compounds, can be used as a natural antioxidant in pharmaceutical and cosmetic industries.