A B S T R A C TThis study aimed at investigating the chemical composition and in vitro antimicrobial activity of juniper (Juniperus communis L.) berries essential oils (EOs), including commercial samples as well as the oil hydrodistilled from berries grown in Portugal, for which few information is available in the literature. The analysis was performed by gas chromatography coupled to mass spectrometry detection (GC/MS) allowing the identification of a total of 97 compounds. The EOs showed different chemical profiles with only one being according to the European Pharmacopoeia 8 requirements. The laboratory-hydrodistilled EO was characterized by its high content in α-pinene (41.6%), followed by β-pinene (27.6%) and limonene (6.4%), commercial EO1 by α-pinene (31.1%), β-myrcene (16.3%) and sabinene (7.5%) and commercial EO2 by δ-cadinene (16.0%), α-pinene (12.2%) and sabinene (9.4%). The distinct chemical profiles were also evidenced by principal components analysis (PCA), with a clear separation of the evaluated EOs. One of the commercial samples, showed the presence of propachlor, a banned herbicide in the European Union. All the EOs showed relevant antimicrobial activity as they presented microbicidal activity against Candida albicans and at least six of the ten tested bacteria. Commercial EO2 showed a higher biological activity, as it was active against all tested microorganisms, which could be related to its higher content in sesquiterpenes, in particular those oxygenated. Overall, results support the use of Juniper communis L. berries EO as an antiseptic in traditional medicine and highlight its potential as a biopreservative that could be used in different industries.