A field experiment was conducted to study the effect of three Trichoderma species, T. harzianum, T. viride and T. virens on root- knot nematode, Meloidogyne javanica infecting peanut plants, compared to commercial product Bio-Nematon^® (Purpureocillium lilacinum) and chemical nematicide of Oxamyl^®. The averages of total microbial soil community, i.e. aerobic bacteria, spore-forming bacteria and fungi in peanut rhizosphere as well as the frequency % of common fungi with different treatments, during growing season, were recorded. Treatments significantly (P=0.05) suppressed J₂ in soil and J₂, females, galls and egg masses in roots and improved peanut plant growth and yield parameters. At mid-season, Trichoderma spp. had more effective nematicidal effects in reducing nematode parameters than Bio-Nematon®  in some cases. The highest percentages reduction in J₂ in soil (being 81%) was recorded with T. viride followed T. harzianum (77%) and T. virens (73%), compared to untreated control. At harvest time, T. viride recorded the highest nematode reduction in J₂ in soil (68%), but T. harzianum recorded the highest reduction in total developmental stages of nematode (68%), galls (84%) and egg masses (84%), compared to T. viride, T. virens and Bio-Nematon^®. The treated soil rhizosphere differed in total microbial counts as well as frequency of common fungi according to the tested treatment that increased total microbial counts. The treatments highly increased the growth and yield criteria of peanut as indicated by fresh & dry weights of plants as well as number & weight of pods and weight of 100 seeds of peanut plants.