Rice blast disease is an important disease but effective biological control agents (BCAs)for controlling the causal organism Magnaporthe grisea, are currently unavailable.Theresearch is aiming to establish an assessment system for creening effective bacteria asbiological control agents using molecular techniques against M.grisea on rice and assess thepotential biological control agents in the greenhouse.935 bacterial isolates were obtained fromthe surface and interior of stems, phyllosphere, rhizosphere, endorhiza, and endosphere offield-grown rice plants and bulk soil and biological control potential according to in vitro andvivo activities of their extracellular metabolites (chitinase, cellulase, glucanase, protease, andsiderophores) was studied.Amplified ribosomal DNA restriction analysis and BOX-PCR
　　analysis were also performed to examine the genetic diversity of 30 isolates with at least onepoint of assessed biological control potential.The thirty isolates achieved positive biologicalcontrol efficacy ranging from 18.08％ to 77.50％ at 45 days post pathogen inoculation (dpi).Iacquired 10 well-performed potential BCAs, especially Bacillus cereus H-S in 24, Bacillussubtilis D-L in 76 displayed good biological control capacity against M.grisea diseases on rice.This demonstrated that H-S in 24 and D-L in 76 in both greenhouse and molecular techniquestests(examining of infectious growth and appressorium penetration on the rice leaf) showedhigh positive results by limiting the effects of M.grisea on the plant.Pearson correlationanalyses of assessment scores and antagonistic test in greenhouse show 0.87 and 0.73 againstM.grisea suggesting that the BCAs screening and assessing system developed is adaptable for
　　controlling rice blast disease.