Objective.To develop monoclonal antibodies again st the catalytic subunit of human telomerase reverse transcriptasefor i ts expression detection of human tumors.Methods.A dominant epitope in hTERT was automatically synthesized based on Fmoc method,and was used to immuni ze Balb/c mice.Hybridomas were generated and screened by ELISA for specific mo noclonal antibodies,and the characterization was performed by Western blotting and immunohistochemical staining.The heavy chain variable region of antibody wa s cloned by RT-PCR and sequenced.Results.Antigenic peptide hTERT 7 was synthesized and confirmed by MALDI-TOF-MS and HPLC analysis.One hybr idoma cell line secreting anti-hTERT 7 antibodies designated as M2was established after primary screening and cons equent 3rounds of limited dilution.M2was IgG1in isotyping.The competi-tive assay showed that the M2antibody was hTERT 7-specific,and the affinity constant was about 1×10 6 mol-1 .The antibody reacted with cell extracts from HeLa cancer cells but not wi th those from normal2BS cells in ELISA assay.For in situ staining of immunohis tochemistry,the positive staining presented in the nuclear compartment of HeLa ,while2BS was negative.The heavy chain variable region from M2re-vealed tha t the monoclonal antibody was mouse origin.Conclusions.The developed mouse mon oclonal antibody is hTERT-specific and able to recognize native cellular hTERT in ELISA and immunohistochemistry,which makes the immuno-detection of telom-e rase hTERT expression in cancer cells or tissues possible. Objective.To develop monoclonal antibodies again in the catalytic subunit of human telomerase reverse transcriptase for i ts expression detection of human tumors. Methods. A dominant epitope in hTERT was automatically synthesized based on Fmoc method, and was used to immunize ze Balb / c mice. Hybridomas were generated and screened by ELISA for specific mo noclonal antibodies, and the characterization was performed by Western blotting and immunohistochemical staining. The heavy chain variable region of antibody wa s cloned by RT-PCR and sequenced. Results. Antigenic peptide hTERT 7 was synthesized and confirmed by MALDI-TOF-MS and HPLC analysis. One hybridal line secreting anti-hTERT 7 antibodies designated as M2was established after primary screening and cons equent 3rounds of limited dilution. M2was IgG1in isotyping. the competi-tive assay showed that the M2antibody was hTERT 7-specific, and the affinity constant was about 1 × 10 6 mol-1. The antibody-reacted with cell extracts from HeLa cancer cells but not wi th those from normal 2BS cells in ELISA assay. For in situ staining of immunohis tt, the positive staining presented in the nuclear compartment of HeLa, while 2 BS was negative. The heavy chain variable region from M2re-vealed tha t the monoclonal antibody was mouse origin. Conclusions. The developed mouse monoclonal antibody is hTERT-specific and able to recognize native cellular hTERT in ELISA and immunohistochemistry, which makes the immuno-detection of telome-e rase hTERT expression in cancer cells or tissues possible.