For valorization and diversification of medicinal plants used in Comoros, we are interested in three species growth in this archipelago. Four essential oils were extracted from these plants and used in this study. Essential oils were obtained by hydrodistillation and analyzed by gas chromatography (GC) and GCâmass spectrometry (GCâMS). Sesquiterpene compounds are predominant in Piper borbonense and Vetiveria zizanoides essential oils but for Piper capense essential oil, monoterpenes are predominant. Essential oils were investigated for their fungicidal activities against four fungi decay wood: Gloeophyllum trabeum (Persoon ex Fries) Murril (ATCC 11539), Poria placenta (Fries) Cooke sensu J. Eriksson (ATCC 9891), Coniophora puteana (Schumacher ex Fries) Karsten (ATCC 9351) and Coriolus versicolor (Linnaeus) Quélet (ATCC 12679). These essential oils showed an in important activity against all strains tested. However, the highest activity was observed in Vetiveria and P. borbonense essential oils.