The chemical composition of the water-distilled essential oil and n-hexane–ether extract of Teucrium leucocladum Boiss. were determined by GLC and GLC–MS. Altogether 72 compounds were identified. The sesquiterpene alcohols, patchouli alcohol (31.24% and 29.66%) and a-cadinol (9.29% and 21.54%) were the main components in the oil and the extract, respectively. a-Cadinol was isolated and characterized using MS, 1 H- and 13C-NMR spectral analyses. Furthermore, the oil and the extract were tested for their bacterostatic and antifungal activities; they showed broad and potent activity against Pseudomonas aeruginosa, Bacillus subtilis and Candida albicans. A marked larvicidal activity of the essential oil, nhexane–ether extract and crude ethanolic extract was also observed against Culex pipiens, Musca domestica and Ceratitis capitata larvae.