The research work presented in this paper was carried out during the two growing seasons of 2005 and 2006 in order to study the influence of foliar application with different levels from active yeast extract (50, 100 and 200 ml/liter) on vegetative growth and volatile oil of River red gum (Eucalyptus camaldulensis Dehn.). The obtained results indicated that the relatively low used concentration of 50 ml active yeast extract per liter showed no significant effect on vegetative growth characters of River red gum plant, aged nine months, in both studied seasons. On the other hand, the other used concentrations of active yeast extract (100 and 200 ml/L.) induced significant increase in plant height, diameter of the main stem, number of branches per plant, mean leaf area, fresh weight of stems per plant, fresh weight of leaves per plant, biomass of shoot per plant and dry weight of shoot per plant of River red gum in both studied seasons. The maximum increase in this respect was recorded at 200 ml YE/L. As to the effect on volatile oil, data revealed that the percentage of volatile oil in leaves of River red gum was increased with increasing the concentration of active yeast extract reaching its maximum at 200 ml YE/L. At the same time, all sprayed concentrations of active yeast extract did not affect volatile oil components. However, the percentages of volatile oil components were slightly affected by the tested treatments.