Cancer is the second cause of death in the world after heart disease. Cancer therapy using natural product was considered has no effect. Secondary metabolites from ketapang (Terminalia catappa L) leaves has a propect for cancer therapy. The objective of this research was to determine the citotoxicity effect of ketapang leaves on T47D breast cancer cells. Ketapang leaves were macerated using chloroform, ethyl acetate and methanol. Citotoxicity effect were determined using MTT Cell Viability Assay. The result showedthat chloroform, ethyl acetate and methanol extract were not able to reduce cellviability of T47D cells