Objective: To investigate the biochemical capacity, and in vitro inhibitory effects of hairy roots from two cultivars of Ficus carica L. (Sabz and Siah) on Leishmania major promastigotes and amastigotes. Methods: In the hairy roots, the activity of antioxidant enzymes compared to normal leaves and roots, and the presence of some phenolic compounds in comparison with fruits were investigated. The IC 50 values of hairy roots in promastigotes was determined by tetrazolium-dye 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide and trypan blue assays. By calculating the infectivity index of peripheral blood mononuclear cells (PBMCs), the leishmanicidal activity (IC 50 values) of hairy roots for amastigotes was estimated. The effects of hairy roots (IC 50 values) treatment on the levels of IFN-γ and iNOS expression, intracellular reactive oxygen species, and iNOS protein expression in infected-PBMCs were determined. Results: Based on antioxidant enzyme assays and high performance liquid chromatography analysis, hairy roots exhibited high antioxidant capacity and contained high levels of phenolic compounds. According to the results of tetrazolium-dye 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide and trypan blue assays, the hairy root extracts of both cultivars showed considerable dose-dependent inhibitory effects against Leishmania major promastigotes. Depending on the concentration and exposure time, treatment of infected-PBMCs with hairy root extracts caused the generation of a significant reactive oxygen species, up-regulation of IFN-γ and iNOS genes expression, and high value of iNOS protein compared to controls. Conclusions: The findings of this study suggest that the hairy roots of Ficus carica can be considered as a promising natural source of antileishmanial agents.