Objective To study lymphocyte subsets changes in patients with malignant tumors during chemoimmunotherapy and the clinical significance. Metheds Fifty one cases were treated with chemotherapy and twenty six cases with chemoimmunotherapy. Lymphocyte subsets were determined by flow cytometry. Results Chemotherapy significantly decreased CD 3 +, CD 4 + and NK cells ( P 0 05). Chemoimmunotherapy elevated CD 8 + and NK cells ( P