Telekia speciosa (Schreb.) Baumg., Asteraceae, is widespread in Eastern and Central Europe and the Balkan Peninsula. Previous phytochemical investigations have revealed T. speciosa as a rich source of sesquiterpene lactone -isoalantolactone, especially in its underground parts. The aim of the present study was to analyze the essential oils from aerial and underground parts of T. speciosa and investigate their antimicrobial activity. Chemical composition of essential oils was determined by GC-FID/MS method leading to the identification of 67 compounds in total, with 15.77 % oxygenated monoterpenes, 7.77 % sesquiterpene hydrocarbons, 49.14 % oxygenated sesquiterpenes, and 12.37 % other compounds from aerial parts, and 3.80 % oxygenated monoterpenes, 3.13 % sesquiterpene hydrocarbons, 90.33 % oxygenated sesquiterpenes from underground parts essential oil. The main components from aerial parts were (E)-nerolidol (11.54 %) and caryophyllene oxide (10.54 %), while isoalantolactone was the predominant component from essential oil underground parts (83.41 %). The minimum inhibitory concentration (MIC), minimum bactericidal/fungicidal concentration of the essential oils were evaluated against six strains of bacteria and two strains of fungus using in vitro microdilution method. Both oils presented antimicrobial properties against pathogens Staphylococcus aureus, Bacilus cereus, Pseudomonas aeruginosa, Escherichia coli, and Candida albicans. Inhibition of growth of tested microorganisms by T. speciosa underground parts essential oil was achieved with MICs ranging from 1.0 to 11.0 mg mL -1 , while MICs of aerial parts essential oil varied from 4.0 to 30.0 mg mL -1 . The obtained results contribute to the knowledge of antimicrobial properties of T. speciosa, which support traditional uses underground parts of the plant.