The chemical composition of the essential oil of Portuguese juniper berries(Juniperus communisL. ssp.nanaSyme) was investigated by means of gas chromatography. This analysis was compared with that of an aqueous alcoholic extract of the juniper berries of similar origin. The qualitative composition of the oil and the alcoholic extract was found to be very similar. The major hydrocarbon components of the oil were α-pinene (20.0%), δ-cadinene (10.4%), limonene (8.7%), and myrcene (8.5%), whereas the alcoholic extract contained α-pinene (11.0%), δ-cadinene (12.8%), β-caryophyllene (9.8%) and germacrene D (9.3%). The main oxygenated constituent in both the oil and the extract was borneol (8.0–8.6% respectively).