The aim of this investigation were to determine and evaluate (in vitro) the chemical composition of leaves and seeds contents for Moringa oleifera (MO), Moringa stenopetala (MS), Moringa peregrina (MP) which were collected from Egypt. The results of the chemical composition analysis showed that Moringa species leaves and seeds have high significant nutritional values. Moisture, ash, protein, fat, fiber, carbohydrate, energy, elements; Ca, Mg, Zn, Cu, vitamins C and A, amino acids compositions, total phenolic contents and antioxidant activities against DPPH free radical were determined. Meanwhile, the oil proprieties evaluated and the results showed significant decreases in; free fatty acids percentage’s, peroxide values, iodine values and showed significant increases for saponification values. Also, the fatty acids compositions were evaluated and the major saturated fatty acids; palmitic acid (C16:0), stearic (C18:0) and behenic (C22:0) recorded high significant values. On the other hand, the main unsaturated fatty acids, oleic acid (C18:1n9); eicosenoic (C20:1n9) and palmitoleic acids (C16:1n7) recorded significant values. In addition to evaluate (in vivo) the effects of ethanolic and aqueous extract of these species leaves on streptozotocin (STZ) induced diabetes rats. Fasting (FBG) and postprandial blood glucose (PBG) levels, ALT, AST, Creatinine, Triglyceride (TG), Total Cholesterol (TC), LDL and HDL were evaluated. Significant reduction p<0.05 was recorded in glucose levels of the diabetic rats compared with diabetic control group expressing their hypoglycaemic potentials. PBG, Creatinine, TC, HDL, LDL levels, ALT and AST activity showed significant decreasing. On the other hand, TC and TG level showed significant decrease compared with diabetic control group. Meanwhile, hisopathological examination for liver, kidney and pancreas tissues showed more improving for group treated with Moringa oleifera than the other groups. That balances and different may referred to many factors; environments, climate, origin, genetic, fertilization, temperature range and flowering and yielding time. Generally, conclusion use of natural antidiabetic of Moringa oleifera leaves might be useful for decreasing PBG level and the effects against pancreatic damage, moreover, improves liver and kidney functions. Key words: Moringa olifera; Moringa stenopetala; Moringa peregrina; Fatty Acids ; STZ; Antidiabetes; Antioxidant; Total Phenolic Contents; DPPH.