Anti-proliferative activities of 143 crude extracts obtained from 32 plants collected from the rain forests of Paliang, Malaysia, were evaluated in two breast cancer cell lines, i.e. MCF-7 and T47D, obtained from the American Type Culture Collection, USA. The objective of this study was to bioprospect a list of plants to Find out their potential to be developed into anti-cancer drug(s), by means of bioassay guided isolation procedure. After performing sulforhodamine-B assay, 13 crude extracts from ll plant species were found to have active anti-proliferative effects (IC30 s 100 pg ml").