Objective : to evaluate the action of Transfer Factor on the immune response of patients with malignant neoplasm submitted to surgery, chemotherapy and radiotherapy. Method: we analyzed the variations of leukocytes, total lymphocytes, T-lymphocytes and CD4 counts in 60 patients submitted to immunostimulation with a single, daily dose of 0.5mg sublingual Transfer Factor, started simultaneously with chemotherapy and/or radiotherapy. Results: there were statistically significant increases in the counts of all cell lines studied, more pronounced after 12 months of use of the medication. Conclusion: the Transfer Factor restored immune response and showed no side effects.