Seven fungi were isolated from five plant hosts collected from 15 governorates. The mean percentage of fungal recovery from the governorates showed that Trichoderma spp. (35.44%) Fusarium spp.(28.45% ),and Rhizoctonia solani(16.00%) were the most dominant fungi, other fungi occurred at frequencies ranged from 1.33 to 7.79 % . Fifteen isolates of Trichoderma spp. were screened for their biocontrol activity against soil- borne fungal pathogens under greenhouse conditions by using eight pathosystems. The tested isolates showed variable levels of antagonism within each pathosystem. When the same isolates were in vitro screened for β-1,3- glucanase,prodution20% of the isolates were high producers, 46.67% were medium producers, and 33.33% were low producers. Regression analysis was used to study the effect of β-1,3- glucanase activity ( independent variable) on percentage of surviving seedlings (dependent variable)in each pathosystem.In almost all pathosystems.the in vitro efficiency of Trichoderma isolates in producing for β-1,3- glucanase was not significantly correlated with the percentage of surviving seedlings, which was used as a parameter for evaluating the antagonistic activity of  Trichoderma isolates under greenhouse conditions. This finding may indicate that the in vitro β-1,3-  glucanase activity of Trichoderma isolates is of no practical value because it cannot be used as a criterion to predict Their in vivo performance .Grouping the isolates by cluster analysis,based on their antagonistic patterns, was not related to their β-1,3-glucanase activity .these results may suggest that β-1,3- glucanase may not be involved in the biocontrol process of the tested isolates. Similary, grouping the isolates by cluster analysis, based on their RAPD banding patterns, was not related to their β-1,3-glucanase activity, this result indicates that RAPD banding patterns were unable to differentiate among the isolates based on their β-1,3-  glucanase activity.