Abstract: Ectomycorrhiza (ECM) and vesicular-arbuscular mycorrhiza(VAM) are the two principal associations on root systems of most vesicle plants worldwide.It is proved that the genus Eucalyptus is capable of forming both ECM and VAM,even at the same root system. This paper represents the third part of the report with results from coinoculation experiment using two fungal isolates (Pisolithus tinctorius and Glomus caledonium),and demonstrates the inoculant effectiveness on the growth of Eucalyptus urophylla Seedlings. The results showed significant differences in growth and biomass between inoculated and uninoculated seedlings (P =0.01). Five months after inoculation, average height and basal diameter of coinoculated seedlings increased by 41.7%～73.8% and 17.2%～19.3% respectively,comparing to that of controls.Additionally, their mean dry weight was enhanced by 194.3%～240.3%. Mycorrhizal dependence (MD) of combined inoculated seedlings ranged from 340.3% to 294.3% based on their top dry weight. The effects on the growth of Eucalyptus inoculated with fungal isolates alone or in competition was also compared.