Pea (Pisum sativum L.) is subjected to attack by certain soil-borne phylogenetic of fungus-like eukaryotic microorganisms such as Pythium debaryanum and soil-borne fungi Rhizoctonia solani and Fusarium solani which cause damping-off diseases. Isolation of associated fungi and P. debaryanum and three species of Trichoderma was carried out from soil rhizosphere of pea plants. Antagonistic effect of Rhizobium leguminosarum combined with Trichoderma lignorum, T. longibrachiatum and T. koningii against pathogenic fungi was investigated in vitro and in vivo under greenhouse conditions. The effect of combinations between the tested Rhizobium sp. and the other tested Trichoderma spp. on the disease incidence caused by the pathogenic microorganisms was evaluated when used as seed and soil treatments. Disease assessments, nitrogen fixation and yield parameters after 50 and 90 days from sowing in comparison with un-treated and fungicide treatments were recorded. Mycoparasitic activity of the tested Trichoderma spp. against each of the pathogenic fungi and Pythium debaryanum was studied using scanning electron microscope. Results showed that the soil treatments were more effective in controlling damping-off disease than seed treatments in overall experiments. Combination of R. leguminosarum with T. longibrachiatum gave the best results in reducing percentage of post-emergence damping-off (13.33 and 6.67%) and root rot (14.72 and 9.58%) caused by P. debaryanum and R. solani, respectively. Survived plants, nitrogen fixation and yield parameters were also increased. Treatment of R. leguminosarum combined with T. koningii against infection by F. solani gave the best results in reducing percentages of post-emergence damping-off (6.67%) and root rot (13.06%) with increment of survived plants, nitrogen fixation and yield parameters. In conclusion, combinations of R. leguminosarum with the Trichoderma species were effective than application of each one alone against pea damping-off disease.