Greenhouse studies were conducted to investigate the effect of root – knot nematode (Meloidogyne incognita) and cowpea wilt caused by Fusarium oxysporum f.sp. tracheiphilum. The effect of the nematode in combination with the fungus enhanced the suppression of plant growth than that of the fungus alone. Inoculation of the nematode and fungus exhibited a synergistic effect on growth retardation of plants. Maximum reduction in plant height (38.08 cm) was observed when nematode and fungus were inoculated simultaneously.