This research was conducted to study the effect of four bacterial strains (PGPR): Pseudomonas chlororaphis MA342, Serratia plymuthica HRO-C48, Bacillussubtillis B2g and B. subtillis FZB27 to improve the growth of tomato plants in the greenhouse. Bacterial strains were applied to the seeds in a concentration of (1010 cfu/ml), of each bacterial strain.