The antagonistic and inhibitory activity of fourteen Bacillus subtilis isolates (B1 to B14) obtained from different Egyptian sites, were tested against six fungal isolates belonging to four different genera, Rhizoctonia solani , Helminthosporium spp., Alternaria spp. and Fusarium oxysporum . Cultural, morphological and physiological characteristics of these isolates were found to be identical to Bacillus subtilis. When the fourteen B . subtilis isolates were tested as biological control agents for their antagonistic effect on the in vitro growth of the fungal isolates, four B . subtilis isolates B1, B4, B7, B8 had more antagonistic effect on all fungal isolates. Supernatant of B . subtilis isolate B7 had antagonistic effect on 6 fungal isolates but it was more effective on Helminthosporium spp., Alternaria spp. and F . oxysporum. B . subtilis as well as, isolate B7 showed effectiveness in reducing disease incidence and severity levels of tomato plants when added to the F . oxysporum and R . solani -infested soil. Also, it stimulated the growth of tomato plants compared to the other. HPLC analysis of the HCl precipitate of B . subtilis isolate B7 culture supernatant revealed that an identical pattern of five peaks to that of a purified preparation of iturin A was obtained.