Abstract: Objective :To explore the possibility of transfusing dendritic cells (DCs) induced from pre-mobilized human peripheral blood stem cells (PBSC) for therapy of breast cancer patients. Methods :PBSCs were collected from 9 breats cancer patient: who were pre-mobilized with G-CSF dy CS-3000plus Blood Cell Separating System. After 7-8 days'culture in medium containing rhGM-CSF and rhIL-4 and exposure to autologou: cancer cell extracts, they became mature DCs and transfused back to the patients. The killing activity of CTLs activated;mature DCs in vitro and in vivo was determined by using MTT method. Results :The average PBSC number collecting from 9 patients was 1.02x 10⁹. After culture,average 2.3 x10⁸ DCs were harvested averagely.The CB83 positive accounted for 68.7% of DCs.DCS harvested this method was 57.5 folds of the equal volume nonmobilized whole blood. CTL induced by mature DCs killed the cultured autologous primary cancer cells powerfully. After DCs transfusion, the patients only felt slight fever and no other side effects,the cytoto7icity of PBMC increased 20 fold than before. Conclusions