The essential oil from the oleoresin of the female cones of C. libani A. Rich. (Pinaceae) grown in Turkey was obtained by the hydro-distillation method and its chemical composition was analyzed by GC and GC-MS. By these methods, about 91% of the compounds in the oil were identified and some high boiling compounds could not be identified. The results showed that the essential oil contained about 38.48% monoterpenes, 33.70% diterpenes, 11.77% oxygenated monoterpenes, 4.67% sesquiterpenes and 0.33% of sesquiterpene alcohols. Major components of the oil are as follows: a-pinene (24.78%), abieta-7,13-diene (16.67%), abieta-8,11,13-triene (6.85%), manool (5.83%) and terpinen-4-ol (3.74%), alpha-terpineol (3.42%), p-cymene (2.89%) and limonene (2.69%). The antimicrobial tests indicated that the oil inhibited all the bacteria and yeasts studied and the activities of the oil against the microorganisms greatly depend on concentration.