Bing De Ling is a Chinese herbal formula that has been used to treat cancer patients for more than a decade. However, the molecular mechanisms behind its anti-tumor efficacy are still elusive. Here, we show that Bing De Ling inhibits cell proliferation in ovarian cancer epithelial cell lines, OV2008 and C13. It induces G1/S arrest in a p53-dependent manner in that this effect is attenuated in OV2008 cells transfected with dominant-negative p53 plasmid. Moreover, we show that Bing De Ling up-regulates p53 transcriptional activities as well as its downstream target genes, such as p21Cip1, MDM2, and MDMX. In addition, Bing De Ling inhibits MDMX-p53 interaction which may result in stabilization and activation of p53. Collectively, our results suggest that the anti-tumor activity of Bing De Ling may be in part due to activation of p53.