The present research work was conducted to investigate an anticancer activity of aqueous and ethanolic extract of whole plant of Amaranthus tricolor Linn. on breast cancer cell line. Ethanolic extracts of dried plant was obtained by soxhlet extraction method and aqueous extracts was obtained by maceration method using ethanolic and aqueous solvents respectively. The obtained extracts were dried and used for investigation of anticancer activity. Anticancer activity of ethanolic and aqueous extracts was investigated by using MCF-7 and MDA-MB-231 breast cancer cell lines. Cytotoxicity of obtained extract was investigated by using MTT assay, neutral red assay and trypan blue assay methods. MTT assay and neutral red assay showed that ethanolic extract was having more cytotoxic activity than that of the aqueous extract were as the results of trypan blue assay method showed that ethanolic and aqueous extract of whole plant have ability to kill viable cells of MCF-7 and MDA-MB-231 cell lines and it was observed that ethanolic extract have ability to show significantly more non-viable cell count than that of aqueous extract. These results suggest that aqueous and ethanolic extract of whole plant of Amaranthus tricolor Linn. Has potential anti-cancer activity.