laboratory studies were carried out to evaluate the efficacy of Lawsonia inermis Linn. (Family: Lythraceae) against the Egyptian cotton leafworm, Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae), Results of the five concentrations (1000,2000,3000,4000 and 5000ppm) of water extract against (1st and 2nd instars) and (3rd and over instars 4th, 5th and 6th) of S. littoralis after 24 and 48 hrs showed that, the S. littoralis mortality significantly increased when water extract concentration increased. Also, results indicated that treatment with water extract affects the biochemical activities of the cotton leafworm S. littoralis. There are an alterations in all tested enzymes (Phenoloxidase, chitinase, protease, alkaline and acid phosphatases) and disturbances in protein levels under investigations when the cotton leafworm S. littoralis treated with Henna extract at all concentrations.