Abstract The essential oils from fresh leaves of Cupressus sempervirens L. were subjected to GC/MS analysis in order to determine seasonal variations in their chemical composition. The plant material was collected within 12 months (1999) in the central part of Dalmatia (Croatia). The qualitative composition of the components appeared to be constant. However there were notable differences in the amounts of several compounds. The main component was α-pinene (28.4â79.2%). Other important components were γ-3-carene (9.1â32.6%), α-cedrol (1.2â12.9%), limonene (1.4â8.7%), terpinolene (0.6â7.0%) and α-terpinyl acetate (0.8â4.5%).