Abstract The chemical composition of the cistus oil from Portuguese-grown rockrose (Cistus ladanifer) was determined using GC and GC/MS. A comparison was also made in terms of the geographical source and use of either dry or fresh plant material. The cistus oil herein obtained was richer in amber-like compounds and had a low content of monoterpenes when compared to the usual values found in the literature. Moreover, it presented a relatively high content of ambrox (amber odor), which usually is only reported in labdanum oil. The major constituents were three sesquiterpene alcohols: viridiflorol (13.6â17.4%), globulol (3.1â5.0%) and an unknown sesquiterpene alcohol (2.7â6.0%), as well as the diterpene alcohol 15-nor-labdan-8-ol (1.7â5.2%). Three samples of commercially available cistus oil were also analyzed and compared. Key Word Index: Cistus ladanifer Cistaceaerockroseessential oil compositionviridiflorol