The chemical composition of essential oils from unripe and ripe fruits of Piper amalago L. var. medium (Jacq.) Yunck and Piper hispidum Sw. was examined using GC/MS analysis. The analysis of oils from P. amalago revealed a predominance of oxygenated sesquiterpenes and 65 compounds were identified; their main constituents are: (E)-nerolidol (14.2% and 19.9%), germacrene-D-4-ol (10.3% and 12.7%), α-cadinol (11.1% and 8.2%) in 99.6% and 98.7% of the compounds for unripe and ripe fruits, respectively. Piper hispidum revealed a predominance of sesquiterpene hydrocarbons, from which we identified 53 compounds including: α-copaene (28.7% and 36.2%), α-pinene (13.9% and 7.1%), β-pinene (13.3% and 7.5%), and (E)-nerolidol (2.9% and 7.0%) which represented 97.8% and 98.1% of the compound constituents for unripe and ripe fruits, respectively. The essential oils of fruits of P. amalago and P. hispidum are reported for the first time. [ABSTRACT FROM AUTHOR]