An experiment was carried out to study the interaction of root knot nematode, Meloidogyne incognita, Paecilomyces lilacinus and plant growth promoting rhizobacteria, Bradyrhizobium on the growth of black gram, Vigna mungo. In the present investigation it was revealed that Meloidogyne incognita resulted in significant decrease in the growth of black gram, root-nodule development, nitrogen contents of root and shoot, and nitrogenase activity at all inoculum levels. Treatment of Bradyrhizobium and Paecilomyces lilacinus resulted in significantly lesser damage to plant growth of blackgram than the plants treated with bacteria at the time of inoculation with rootknot nematode, M. incognita fallowed by plants where bacteria and fungus was applied 10 days after nematode inoculation. .Treatment of Bradyrhizobium significantly increased the nitrogen content of root and shoot in all the treatments. Nitrogenase activities in nematode infected plants was higher in plants treated with P. lilacinus and Bradyrhizobium before and at the time of nematode inoculation in comparison to plants which were treated by P. lilacinus and Bradyrhizobium 10 days after nematode inoculation.