Aloe-emodin is a Hydroxyanthraquinone that exists in Aloe Vera leaves and has been known to have antitumor effects. Various studies have shown the biologic effects of Aloe Vera such as antiviral, antimicrobial and some other hepato-protective effects. Recently its antitumor effects have attracted many researchers. Breast cancer is the most common malignancy in women, accounting for 30% of all female cancers and< 1% of all cancer cases in men. Breast cancer also is responsible for 15% of cancer deaths in women. The aim of the present study was to investigate the anti-cancer effect of aloe-emodin on human breast cancer MCF-7 cell line. MCF-7cells were cultured in RPMI medium with 10% fetal bovine serum (FBS). The cytotoxic effect of different concentrations (5, 10, 25, 50, and 100 µM) of Aloe-emodin on cultured cells were evaluated by MTT assay at different times (24, 48, 72 h). Apoptosis and CD95 (Fas) expression were analyzed by flow cytometry using an AnnexinV-FITC/PI kit and Fas (CD95) kit according to the manufacturer’s protocol. Aloe-emodin decreases the viability of MCF-7 cell line in a time and dose dependent manner, so that the most effective concentration of this substance was 100µM and 72h after treatment. According to the data of Fas (CD95) expression and Annexin-PI, the highest apoptosis induction rate was seen in 100µM and 72 h. The findings of the present study indicated that Aloe-emodin has some antitumor effects and can be used in the treatment of breast cancer. However, further investigation, both in vitro and in vivo, of its cytotoxic effects against tumor cells is recommended.