Analysis of wood essential oil of Cupressus dupreziana revealed 26 components: 13 monoterpenes and 13 sesquiterpenes. The main components were carvacrol methyl ether and cedrol. A petrol extract of Cupressus sempervirens wood was investigated and showed a mixture of sesquiterpenes very similar to those found in Cupressus dupreziana. The biogenesis of the identified sesquiterpenes is discussed.