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 (13.6-17.4%), globulol (3.1-5.0%) and an unknown sesquiterpene alcohol (2.7-6.0%), as well as the diterpene alcohol 15-nor-labdan-8-ol (1.7-5.2%). three samples of commercially available cistus oil were also analyzed and compared. key word index: cistus ladanifer cistaceaerockroseessential oil compositionviridiflorol