The efficient protection of the root system against phytopathogens by Trichoderma strains dependent on their establishment in the rhizosphere. The potential of 13 wild type strains from Trichoderma different species to colonize tomato root was investigated in a full-rinsed sandy soil, in which seed and root exudates were only nutrient source for the Trichoderma growth. CFU analysis and SEM images showed, all used strains successfully propagated in spermosphere and continued their growth in rhizoplane simultaneously root enlargement. The Trichoderma population was significant between used strains and different depths for each strain. The depth had also a more significant effect on CFU numbers of strains with lower segments than the top segment. The strains T6 and T7 were the most abundant in the apical segments compare to all the other treatments. Root colonization in most strains associated with promoting the roots and shoots growth while they significantly increased up to 43% and 40% roots and shoots dry weights, respectively. These observations suggest a difference in rhizosphere competency between these strains. The ecological different performance leads us to obtaining the strains which entirely colonize root surfaces during growth period in strain screening for strain improvement and commercial bio-producing

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