The essential oil constituents of aerial parts of Phagnalon sordidum (L.) Rchb. were analyzed by a combination of capillary gas chromatographic-flame ionization detector (GC-FID) and chromatography-mass spectrometry (GC-MS). A total of 125 constituents comprising 97.6 % of the total oil were identified. The volatile fraction was characterized by monoterpene hydrocarbons (51.4 %), oxygenated monoterpenes (10.4 %), sesquiterpene hydrocarbons (18.0 %), oxygenated sesquiterpenes (6.0 %) and non-terpenic components (11.8 %). The predominant constituents identified were β-pinene (26.0 %), (E)-β-caryophyllene (10.0 %), limonene (8.5 %), myrcene (4.7 %), decanal (4.5 %), thymol (3.9 %), germacrene-D (3.8 %), and p-cymene (3.4 %). The antimicrobial activities of the essential oil evaluated against eleven bacteria and Staphylococcus aureus, Klebsiella pneumoniae and Salmonella typhimurium were the most susceptible microorganisms with a minimum inhibitory concentrations (MICs) 0.01, 0.04, 0.04 mg/mL respectively. Additionally, the essential oil showed moderate radical scavenging and electron donating activity.