Ethnopharmacological relevance: Smilax china L., referred to 'Ba Qia' (or 'Jin Gang Teng') in China, is a small vine that grows in the southern parts of China. The roots and tubers of S. china L. have been applied not only as traditional Chinese medicine (TCM) for treatment of diuretic, rheumatic arthritic, detoxication, lumbago, gout, tumor, and inflammatory diseases, but also as food in some area of China. Aim of study: To investigate the breast tumor cell toxic components in S. china L. continuously and systematically. Materials and methods: Three fractions and six polyphenols were isolated from roots and tubers of S. china L. under bioassay-guided screenings. The structures of six compounds were elucidated by spectroscopic methods and comparison with published data. Their breast tumor cytotoxicity and apoptosis of purified components were performed. Results: Six polyphenols were obtained on the basis of a bioassay-guided separation of the ethyl acetate extract, and their breast tumor cytotoxic activities were tested. They showed anti-tumor activities against MCF-7 and MDA-MB-231 with IC50 value of 2.1-38.9 μg/mL, and can induce apoptosis for MCF-7 and MDA-MB-231. Conclusions: Among these six polyphenols, five (1, 3-6) were reported for the 1st time with in vitro activities on anti-breast tumor cell. It is likely that these polyphenols are the active components of S. china L. responsible for the anti-breast tumor cell activities. © 2010 Elsevier Ireland Ltd.