Abstract: Background and Objective: In Egypt, peanut is one of the most important crops for exportation and local consumption. It is a good source of dietary proteins and contains high lipid that is rich in unsaturated fatty acids. Damping-off and root rot diseases are the main constraints in peanut production. The current study aimed to determine the effect of cell-free filtrates of Trichoderma harzianum (T), Saccharomyces cerevisiae (Y) and/or Rhizobium japonicum (R) on the control of damping-off and root rot diseases in peanut. Materials and Methods: Fusarium solani, Rhizoctonia solani and Sclerotium rolfsii were the common causal pathogens isolated from naturally infected peanut, causing damping-off and root rot diseases. Peanut seeds cv. Giza 6 were soaked for 4 h in each tested treatment before sowing; treatments also used as a foliar spraying at 28 days from sowing. While, fungicide Rizolex-T50 was used as seed coating at 3 g kg–1 seeds. Results: In the in vitro tests, the combined application of T+Y+R culture filtrates at the rate of 1:2:1 and the dual application of T+Y completely inhibited the mycelial growth of the pathogenic fungi. While, R alone had no significant effect on the fungal linear growth. In vivo, the best protection against damping-off and root rot diseases were observed under fungicide (Rizolex-T50) application followed by the combination of T+Y+R (1:2:1). All culture filtrates of T, Y, R and their combinations stimulated the activity of polyphenol oxidase, peroxidase and chitinase. The highest activity was obtained by the combined application of T+Y+R (2:1:1) for polyphenol oxidase and peroxidase. While the highest chitinase activity was observed with Y treatment alone. The application of T+Y+R increased the percentage of plant survivals and improved plant growth and yield. Conclusion: The application of a mixture of biotic culture filtrates was more effective in decreasing the infection of soil borne fungi in peanut. Wherein, a commercial production of a mixture of growth filtrates of T+Y+R is recommended for therapy both damping-off and root rot diseases in peanut plant.