Nigella sativa was screened for phytochemical constituents such as alkaloids, flavonoids, tannins, phenols, saponins, carbohydrates, glycosides, sterols, terpenoids and proteins. The antidiabetic activity of N.sativa by Alpha- Amylase and Alpha-Glucosidase assay method showed that the Ethyl Acetate extract had the highest percentage of inhibition against α-Glucosidase than α-Amylase, which reveals the hypoglycemic nature of N.sativa. Investigation of Total antioxidant activity by the phosphomolybdenum method suggested that Ethyl Acetate extract of N.sativa has significantly higher activity than n-Butanol extract at low concentrations than Ascorbic acid. The results confirm the antidiabetic activity of N.sativa seeds extract and suggest that because of its antioxidant affect it may be useful in helping out with the diabetic complications