Abstract: This study was conducted to investigate the suppression effect of some antagonistic fungi and cyanobacterial species against Rhizoctonia solani as the causal agent of soybean root rot. Growth of Rhizoctonia solani as the causal agent of root rot of soybeans was inhibited (in vitro and greenhouse conditions) in the presence of some antagonistic fungi (Gliocladium deliquescens, G. virens, Trichoderma hamatum and T. harzianum) and cyanobacterial species (Nostoc entophytum and N. muscurum). The results show that Trichoderma harzianum was the best antagonistic fungi whereas Nostoc entophytum as cyanobacteria showed antifungal activity higher than Nostoc muscurum, the inhibitory effect was dependant on the type of the bioagent. In experiments carried out in greenhouse, the growth parameters (length, weight, carbohydrate, protein and nitrogen) of the infected soybean plants showed different responses to the tested biological agents as compared to untreated infected plant. It could be concluded from the obtained data the fruitful use of the tested biotic factors for controlling rot root of soybean induced by Rhizoctonia solani.