Abstract: Objective :To assess the influence of chemotherapeutics on T cellular immunity and T cell subsets excluding the influence of malignant tumors. Methods :T lymphocytes were acquired from the peripheral blood of a normal adult. The effect of chemotherapeutic drugs on T lymphocytes was measured with MTT. The capability of T lymphoblast transformation was evaluated by observation of morphologic changes of T cells via an upsidetown microscope in 48h hours, after T cells incubation with PHA respectively. T cell subsets were measured with flowcytometry before and after the administration of chemotherapeutic drugs. Results :Chemotherapeutic drugs have high cytotoxicity T lymphocytes at the high level of dosage, but no change the ration of T cell subsets. Conclusions :Cellular immunity can be suppressed by chemotherapeutic drugs, which has a high nonselective c ytotoxicity to immune effector cell. The progression and regression of tumors is the main factor influencing the celluar immunity and T cell subsets. Chemotherapy just plays an adjuvant role with a change of the relationship between the lbody and tumor.