We have evaluated the medicinal properties of Eucalyptus essential oils that are highly flammable and contains compounds which are natural disinfectants and pest deterrents. The essential oils isolated by hydro distillation from the leaves of four Eucalyptus species growing in Egypt were analyzed by GG/MS for their chemical compositions. The major components identified in E. citridora Hook oil were 3-hexen-l-ol, cis-geraniol, citronellol acetate, 5-hepten-l-ol, 2,6-dimethyl and citronellal; in E. camaldulensis Dehn. were megastigma-3,7(Z),9-triene, dihydrocarveol acetate, cis-nerolidol, kauran-18-al,17-(acetyloxy)-,(4.β.)- and (-)-spathulenol; in E. gomphocephala Dc. were dihydrocarveol acetate, p-cymene and citral (isomer 1) cis-, trans-.; and the major components of E. resinfera Sm. were eucalyptol, (-)-spathulenol, α-terpineol acetate and trans-nerolidol. The findings demonstrated that there are broad differences in the chemical components for the investigated Eucalyptus species.