Objective: To study the expression level of TRF1 (telomeric repeat binding factor 1) protein in human acute leukemia and relationship between expression level of TRF1 protein and telomerase. Methods: A quantitative Western-Blot technique was developed using anti-TRF133-277 monoclonal antibody and GST-TRF1 purity protein as a standard to further determine the ex-pression level of TRF1 protein in total proteins extracted from clinical specimens. Results: Bone marrow tissues of 20 acute leukemia patients were studied, 11 healthy donors’ bone marrows were taken as a control. The expression level of TRF1 protein was significantly higher (P<0.01) in normal bone marrow ((2.217±0.462) μg/μl) than that of acute leukemia patients ((0.754±0.343) μg/μl). But there was no remarkable difference between ALL and ANLL patients ((0.618±0.285) μg/μl vs (0.845±0.359) μg/μl, P>0.05). After chemotherapy, TRF1 expression level of patients with complete remission elevated ((0.772±0.307) μg/μl vs (1.683±0.344) μg/μl, P<0.01), but lower than that of normal ((2.217±0.462) μg/μl, P<0.01). There was no significantly difference after chemotherapy ((0.726±0.411) μg/μl vs (0.895±0.339) μg/μl, P>0.05). TRF1 expression level of patients with complete remission is higher than that of patients without complete remission ((1.683±0.344) μg/μl vs (0.895±0.339) μg/μl, P<0.01). All samples were determined for telomerase activity. It was confirmed that the activity of telomerase in normal bone marrow was lower than that of acute leukemia patients ((0.125±0.078) μg/μl vs (0.765±0.284) μg/μl, P<0.01). There was no significant difference of expression level of TRF1 protein between ALL and ANLL patients ((0.897±0.290) μg/μl vs (0.677±0.268) μg/μl, P>0.05). After chemotherapy, telomerase activity of patients with complete remission decreased ((0.393±0.125) μg/μl), but was still higher than that of normal ((0.125±0.078) μg/μl, P<0.01). Conclusion: The expression level of TRF1 protein has corre-lativity to the activity of telomerase (P<0.001). Objective: To study the expression level of TRF1 (telomeric repeat binding factor 1) protein in human acute leukemia and relationship between expression level of TRF1 protein and telomerase. Methods: A quantitative Western-Blot technique was developed using anti-TRF133-277 monoclonal antibody and GST-TRF1 purity protein as a standard to further determine the ex-pression level of TRF1 protein in total proteins extracted from clinical specimens. Results: Bone marrow tissues of 20 acute leukemia patients were studied, 11 healthy donors’ bone marrows were taken as a control. The expression level of TRF1 protein was significantly higher (P <0.01) in normal bone marrow ((2.217 ± 0.462) μg / μl) than that of acute leukemia patients ((0.754 ± 0.343) μg / μl) After no significant difference between ALL and ANLL patients (0.618 ± 0.285 μg / μl vs 0.845 ± 0.359 μg / μl, P> 0.05) After chemotherapy, TRF1 expression level of patients with complete remission elevated (0.772 ± 0.307 ) μg / μl vs (1.683 ± 0.344) μg / μl, P <0.01), but lower than that of normal ((2.217 ± 0.462) μg / μl, P <0.01) / μl vs (0.895 ± 0.339) μg / μl, P> 0.05). TRF1 expression level of patients with complete remission is higher than that of patients without complete remission (1.683 ± 0.344) μg / μl vs (0.895 ± 0.339) μg / μl, P <0.01). All was found that the activity of telomerase in normal bone marrow was lower than that of acute leukemia patients ((0.125 ± 0.078) μg / μl vs (0.765 ± 0.284 ) μg / μl, P <0.01). There was no significant difference of expression level of TRF1 protein between ALL and ANLL patients ((0.897 ± 0.290) μg / μl vs (0.677 ± 0.268) μg / μl, P> 0.05). After chemotherapy, telomerase activity of patients with complete remission decreased ((0.393 ± 0.125) μg / μl), but was still higher than that of normal ((0.125 ± 0.078) μg / μl, P <0.01) Conclusion: The expressio n level of TRF1 protein has corre-lativity to the activity of telomerase (P <0.001).