Abstract： Objective To investigate the early diagnostic value and significance of telomerase activity by fine needle aspiration in breast neoplasms tissues,in order to provide basis for clinical application.Methods The tissues of 86 patients which obtained by B-ultrasound guided fine needle aspiration were detected by both telomerase activity and cytologic examination,and compared with general tissue specimen after operation.Results Sixty-seven patients were diagnosed as breast neoplasms after operation.The telomerase activity positive rate by fine needle aspiration was 91.0％ (61/67),the cytologic examination positive rate was 88.1％ (59/67).Benign lesion was 19 patients.The telomerase activity positive rate was 26.3 ％ ( 5 / 19 ),the cytologic examination positive rate was 10.5 ％ ( 2/19 ).The specificity of telomerase activity was 73.7％(14/19),the sensitivity was 91.0％(61/67).The specificity of cytologic examination was 89.5％(17/19),the sensitivity was 88.1％ (59/67).The specificity between the two methods had no significant difference (P＞0.05),but the sensitivity had significant difference (P＜0.05).Postoperative breast neoplasms detection of telomerase activity positive rate was 92.5％ (62/67).The telomerase activity positive rate coincidence of general tissue specimen after operation was 98.4％(61/62).Nineteen patients was benign mammary gland disease,the telomerase activity positive rate was 10.5％ (2/19).The telomerase activity positive rate had no significance compared with general tissue specimen (P＞0.05 ).The telomerase activity positive rate had significant relationship with neoplasms diameter,TNM classification,partial nodular transfer (P＜0.05).Conclusions Telomerase activity by fine needle aspiration is a good auxiliary diagnosis technique for breast neoplasms.It can also be used to assess the tumor progression indirectly.