The present investigation was carried out to determine the interrelationship of arbuscular mycorrhiza (AM) fungi with root-knot nematode Meloidogyne incognita and their effect on carbon and nitrogen metabolism of Lagenaria siceraria (Molina) Standley, a mycorrhizal plant of family Cucurbitaceae. Biochemical analysis including carbon and nitrogen profiles was taken into account. The estimation of carbon profile comprising of carbohydrate, glucose, sucrose and total soluble sugars and nitrogen profile comprising of proteins, amino acids protease and proline. Results showed that carbon profile in plant treated with AM fungi have high to low and varied amount of carbohydrates, sucrose, glucose and total soluble sugars in different parts of the plant; amino acids and proline in nitrogen profile found in higher amount in AM treated plants.