abstract the essential oil from fresh leaves of piper cernum veil. var. cernum yuncker from rio de janeiro, brazil was isolated by hydrodistillation and analyzed through a combination of gc and gc/ms. compounds representing 92.9% of the oil volatiles were identified. twenty six constituents were identified according to their retention indices and mass spectra. the major constituents of the oil were cis-dihydroagarofuran (32.3 %), -pinene (10.2 %), -pinene (7.4 %), 10-epi--eudesmol (7.1 %) and elemol (6.7 %).