Objectives : Many of currently used anti-cancer drugs were developed to target cell death mechanisms and had serious side effects by causing damage to normal cells. Hangambujeongsan or Kangai Fuzheng Powder was a mixture based on the traditional Chinese medicine. It had been used in the local Chinese hospitals to treat cancer patients for decades and had shown a certain level of beneficial effects without major toxic effects. But its mechanism of action had not been elucidated yet. Thus this study aimed to investigate the effects of Kangai Fuzheng Powder in an in vitro experiment. Methods : Cancer lines or RAW264.7 mouse macrophage cells were treated with Kangai Fuzheng Powder. Cell viability was measured by MTT assay, and morphological observation was also performed. Gene expression of cytokines in macrophages was determined by real-time polymerase chain reaction. Phagocytic function assay was also performed in macrophage cells. Results : Kangai Fuzheng Powder had no direct detrimental effect on cancer cells. When macrophages were co-cultured with cancer cells, Kangai Fuzheng Powder had toxic effect on cancer cells. After exposing macrophages to Kangai Fuzheng Powder, macrophages transformed into activated form and the mRNA level of tumor necrosis factor-alpha, interleukin-1beta, interleukin-6, interleukin-10 and monocyte chemotactic protein-1 was significantly enhanced. Phagocytic activity of macrophages was dramatically potentiated. Conclusions : We demonstrated that anti-cancer effect of Kangai Fuzheng Powder was related to activation of macrophages including enhanced cytokine production and phagocytic function.