Chemical analysis of the essential oil of Juniperus thurifera wood led to the identification of fifty-eight sesquiterpene compounds, of which twenty-eight have been isolated, two of them being new natural cedrane derivatives (1 and 2). Their structures were established on the basis of 1D NMR and 2D NMR spectra. The antimicrobial activities of different pure compounds of this oil were tested against nine microorganisms (Gram-positive and Gram-negative bacteria, and yeasts). Seven of the tested compounds exhibited a relevant activity, with the known alpha- and beta-cedrenes and sesquithuriferol showing minimum inhibitory concentrations of 3.06 microg/mL against Bacillus subtilis and Proteus sp.