Abstract: Objective To study the anti-tumor effect of Sanjie Kangliu (swelling-dispersing) Decoction in vivo and in vitro. Methods The mice bearing tumors (established by subcutaneous inoculation of SRS-82 cells) were fed with Sanjie Kangliu Decoction. The tumor was isolated and weighed to calculate the tumor inhibition rate, followed by morphological observation of the tumor cells under electron microscope. The DNA of the tumor cells was then extracted for agarose gel electrophoresis. In the in vitro experiment, cultured SRS-82 cells were treated with the serum of rats fed with Sanjie Kangliu Decoction, and the cell viability and apoptosis was examined by MTT assay and flow cytometry, respectively. Immunocytochemistry was employed to test the expression intensity of Bcl-2 protein of the rat serum-treated cells, and in situ hybridization performed to detect matrix metalloproteinase (MMP)-2 mRNA expression. Results In the tumor-bearing mouse models, Sanjie Kangliu Decoction administration resulted in significant reduction of the tumor mass and apoptosis of the tumor cells as shown by typical apoptotic changes of the cell morphology and presence of DNA ladder in agarose gel electrophoresis. In comparison with the mice without the decoction treatment, the treated mice showed significantly lower tumor cell viability, higher cell apoptosis rate, and weaker Bcl-2 expression. The expression of MMP-2 mRNA showed no distinct difference between the groups. Conclusion Sanjie Kangliu Decoction has obvious anti-tumor effect both in vivo and in vitro possibly through the mechanism of inducing tumor cell apoptosis by reducing Bcl-2 expression without affecting the expression of MMP-2 mRNA.