Oregon EO has antiparasitic, antibacterial, antifungal and antioxidant properties. Also, it is used as culinary herb or preservative [10; 11; 12]. The genus _Thymus_ consists of about 215 species that grow in hot and dry climates. _Thymus vulgaris_ is native to southern Europe and it has been cultivated for its culinary and spice properties. The EO extracted from _Thymus vulgaris_ has antimicrobial, antiviral and antisptic activities and it contains geraniol, linalool, gamma-terpineol, carvacrol, thymol and _trans_-thujan-4-ol/terpinen-4-ol. The chemical composition of the EO depends on the growth region and the environment [13; 14; 15]. _Cymbopgon flexuosus_ (lemongrass) belongs to the family Poaceae and is a medicinal grass which is used as a food, perfumery and in pharmaceutical industries [16]. Previous studies showed the antimicrobial effect of lemongrass EO. It is mainly formed from monoterpenes such as citral [17; 18; 19]. The plant _Melaleuca alternifolia_ belongs to the Myrtaceae family which grows throughout South America, Australia and western India. It is used in food, medicine, agriculture and cosme. Named also as tea tree, it is reported to be an antimicrobial agent [20; 21; 22; 23; 24]. The major constituents are terpinene-4-ol, \(\gamma\)-terpinene, and \(\alpha\)-terpinene, 1,8-cineole. Other constituents are \(\rho\)-cymene, terpinolene and limonene. the composition of _M. alternifolia_ EO is influenced by climatic and local conditions. Terpinen-4-ol is the active ingredient responsible for the therapeutic properties. The terpen have the ability to change the permeability of the pathogen's cellular membrane [20; 22]. _Eugenia carryophila_ (clove), is a tree which belongs to Myrtaceae family, and grows naturally in East Indonesia, and its cultivated in many countries such as Brazil, Tanzania, and India. The oil extracted from the tree has major components such as eugenol, gcaryophyllene, \(\alpha\)-humulene, carophyllene oxide and eugenyl acetate. Clove EO exert biological and pharmacological activities. It also has an antibacterial, antioxidant and antimycotic effect [25; 26]. Sodium hypochlorite (NaOCl) is commonly used for root canal disinfection. Previous studies confirmed the use of NaOCl against _E. faecalis_ as a very potent root canal irrigant and after the reaction with water, it releases chlorine, which can be unpleasant for patients. Also, the organic tissue-dissolving properties of NaOCl are non-selective, meaning that it is capable of indistinguishably dissolving both vital and necrotic remnants of pulp, therefore being toxic to periapical tissues. Cytotoxic and genotoxic effects on human peripheral lymphocytes have been studied when applying sodium hypochlorite on human peripheral lymphocytes in vitro [27; 28; 29; 30; 31]. Due to the possible side effects of the synthetic irrigants and to safety concerns the interest in natural alternatives has grown in the last few decades and the most important of these are the products that can be obtained from plants, which have many medicinal and antimicrobial properties [17]. Some previous studies reported the efficacy of different plant extracts against the _E. faecalis_ which concluded that the plant compounds can be used as a possible alternative to NaOCl [31]. The aim of the study was to assess the antibacterial properties of non-chemical, natural root-canal irrigants. Being a preliminary study, the antibacterial effects of five aqueous extracts of essential oils were screened against _E. faecalis_, one of the bacteria that are involved in chronic periodontitis and failed root canal treatments.