Objective: To evaluate the effect and safety of neoadjuvant chemotherapy combined with PA-MSHA injection for breast cancer patients. Methods: An open randomized controlled clinical trial was con-ducted. Fourty patients with breast cancer were randomly assigned to neoadjuvant chemotherapy group (the control group, n=20) and neoadjuvant chemotherapy combined with PA-MSHA injection group (the experi-ment group, n=20). The evaluation of therapeutic effect was carried out when the treatment was completed. Kamofsky score was recorded before and after therapy. Venous blood was drawn before and after therapy and immune function (IFN-γ, IL-2, IL-4, and IL-10) and other indicators (Caspase-3, VEGF, MMP-2 and MMP-9) were measured by double antibody ELISA test. Adverse effects of PA-MSHA during therapy were ob-served and recorded. Results: The overall response rate (RR) in the experiment group was significantly higher than that in the control group (P<0.05). No significant difference was found in the pathologic complete remis-sion (pCR) between the experiment group and the control group (P>0.05). In the experimental group, pCR was significantly different before and after therapy (P<0.01). The score in the experimental group was signifi-cantly higher than that in the control group after therapy (P<0.01). With the treatment of chemotherapy and PA-MSHA injection, IFN-γ and IL-2 levels were significantly higher while IL-4 and IL-10 levels were significant-ly lower in the experiment group (P<0.05). A significant increase in serum Caspase-3 and a significant de-crease in serum VEGF, MMP-2 and MMP-9 (P<0.05) after therapy were also observed in the experimental group. The level of serum MMP-9 was decreased significantly (P=<0.05) after therapy in the control group. Con-clusion: Neoadjuvant chemotherapy combined with PA-MSHA injection can significantly improve the RR of breast cancer patients, enhance their cellular immune function, induce the apoptosis and restrain the metasta-sis of breast cancer cells. The PA-MSHA has been proved to be an ideal supplementary therapy for breast cancer.