An afforestation of mixed plantation was proposed to provide wood supply and minimise exploratory actions in a biological reserve. Eucalyptus plants were indicated for this purpose. This study was carried out to test the effect of volatile oils extracted from the leaves of Eucalyptus camaldulensis Dehn. and E. grandis Hill ex Maiden on the growth of Enterolobium contortisiliquum (Vell.) Morong. Under laboratory conditions, the Enterolobium plants showed tolerance to E. grandis oil, whereas E. camaldulensis oil caused loss of leaves, inhibition of height and diameter growth and a concomitant decrease in effective PSII quantum yield and the reduction of photosynthetic electron-transport chains. The field growth of E. contortisiliquum was not modified by intercropped E. grandis plants, confirming its tolerance. Inoculation with rhizobia and or mycorrhizal fungi significantly improved the height and diameter growth of these species. The results showed that E. contortisiliquum plants could be intercropped with E. grandis for reforestation and agroforestry systems.