Leishmaniasis is wide range, worldwide, without drug, vaccine, secticide and has not sterile immunity and efforts in this field have not been successful. Herbaceous plants tomentose perennial official Siah Daneh and scientific name Nigella sativa. Nigella sativa L. is an annual dicotyledonous of Ranunculaceae family known commonly as “Siah Daneh” (Persian) and “Black Cumin” (English). Many therapeutic effects of Nigella sativa, such as: antibacterial, antifungal, anti- helminthes, antiprotozoan, anti- inflammatory, antioxidant is reported. The present study was carried out to antileishmanial activity of Nigella sativa extract against Leishmania major: An In vitro study. Amastigote was isolated from mice spleens and then transformed to promastigotes in Novy-Nicolle-Mac Neal (NNN medium supplemented with penicillin (100 U/ml), streptomycin (100μg/ml) and 20% heat-inactivated fetal calf serum (FCS) at 25°C. A fixed initial density of the parasites was transferred to screw-capped vials containing 5 ml of RPMI1640 media to which different concentrations of 0.8, 4, 20 and 100 μg NSE were added and each concentration was done in triplicates. Each run also included control. The mortality of parasitoids was measured by the enzyme-linked assay (ELISA) methods. After 72 hour, the percent inhibition was supper in all doses in stationary and logarithmic phases. As shown, after 48hour, viability of parasites in PMs significantly decreased in NSE 0.8, 4, 20 and 100 μg treatment compare to control group. The results show that NSE could prevent from growth and viability of parasites and this can be useful for treatment of Leishmaniasis.