Background: Leishmaniasis, has created enormous global health problem. Side effects, drug resistance and the lack of effective vaccines and to make the new compounds effective due to plant.Objective: The traditional medical plants such as black alfalfa can be a valuable source of new pharmaceutical agents against leishmaniasis.Methods: Alcoholic extracts were prepared by maceration method. L. major promastigotes (Leishmania major) in Schneider and then were cultured in RPMI- 1640. Then, using MTT (Methyl Thiazole Tetrazolium), the IC50 (Inhibitory Concentrations 50%) for extract and Glucantime was determined. MTT assay did for each sample, 3 times.Results: IC50 for alcoholic extract of alfalfa black against L. major promastigotes in vitro after 24, 48 and 72 hours, respectively 165, 98 and 45 micrograms per ml and for Glucantime also equal to 27, 12 and 8 mg l respectively. IC50 between Extract and Glucantime after 24, 48 and 72 hours there was a significant difference (P <0.05). Morphological changes after challenge with meglumine and alcoholic extracts including cell shrinkage, round, dense cytoplasm and the cell was smaller. Presence of alkaloids and flavonoids in alcoholic extracts have been proved.Conclusion: As regards, plant extract had anti- leishmanial effects in vitro, further works are required to appraise the exact effect on Leishmania agent in animal models.