Purpose: To observe the effects of electroacupuncture therapy on T cells and activity of NK cell in the patient of Chemotherapy. Method: Electro-acupuncture therapy was simultaneously applied during chemotherapy, T cells and activity of NK cell of patients were determined before electroacupuncture treatment (before chemotherapy) and after 4-course electro-acupuncture treatments. Results: Before chemotherapy, CD3 was low within the normal range, CD4 was much lower than the normal range, and CD8, CD4/CD8 and activity of NK cell were within the normal range. After one month of chemotherapy combined with electro-acupuncture, no decline of all the indices was found (P>0.05). Conclusion: Electro-acupuncture can really increase the immune function of patients of chemotherapy.The suppression of both immunity and hematopoiesis caused by chemotherapy is mainly characterized by declines of T cells subpopulations (CD3, CD4, CD8), activity of NK cell, WBC count and humoral immunity. Since 1996, the authors have applied electro-acupuncture therapy for 28 cases of malignant tumor in the process of chemotherapy with good results as reported in the following.