Chitinase and ß 1, 3 glucanase activities in susceptible and tolerant cucumber roots pre-colonized with Funneliformis mosseae against root knot-nematode Meloidogyne incognita were studied. Mycorrhizal plants which pre-colonized for 7 weeks inoculated with 1500 J₂ per 1 kg soil. The quantitative activity of chitinase and ß 1, 3 glucanase enzymes was assessed on 2, 4, 6 and 8^th days after M. incognita inoculation based on split- plot in time design. Also the results showed that AMF pre-inoculation caused a significant decrease in RKN pathogenicity factors (number of galls, eggs, egg sacs and J₂) in both tolerant and susceptible cultivars. Inoculation of susceptible roots with AMF significantly reduced the nematode pathogenicity factors. Also the results indicated that the activity of both enzymes increased in the plant with AMF compared with the cucumber roots inoculated with M. incognita alone. Cucumber mycorrhizal roots showed the highest mean activity of chitinase and ß 1, 3 glucanase respectively on the 4^th and 6^th days after M.i inoculation. Preinoculation of AMF increased significantly the activity of both enzymes in cucumber cultivars inoculated with nematode. Although, the level of chitinase and ß 1, 3 glucanase enzymes in tolerant cucumber was significantly higher than susceptible on different days. We concluded that ‘increasing cucumber tolerance to root-knot nematode can be related to involvement of chitinase and beta-1,3-glucanase. So vesicular arbuscular mycorrhizae can be considered as a suitable option for biocontrol of the root-knot nematodes.