The aim of this study was to define the clinical implications of semi-quantitative telomerase activity in gynecological tumors by comparing the telomerase activity of cancerous lesion and the adjacent non-cancerous lesion. In 118 cases of gynecologic tumors, including 41 uterine cervical tumors, 43 uterine body tumors and 34 ovarian tumors, telomerase activities were determined using TRAPeze telomerase detection kit for the extension reaction of the telomere sequence and the PCR reaction for amplification of the sequence, and using fluorecence-based telomere repeat amplification protocol (F-TRAP) method for the detection. In all gynecologic cancers examined, telomerase activity of the cancerous lesion was significantly higher than that of the non-cancerous lesion. Telomerase activity in the uterine cervix increased in the following order of the normal uterine cervix, cervical dysplasia and cervical cancer. Regarding the endometrial cancer, telomerase activity at the primary lesion in patients with lymph node metastases was significantly higher than that in patients without lymph node metastases. When telomerase activity was compared by histologic subtypes of the ovarian cancer, clear cell adenocarcinoma showed significantly lower telomerase activity than the other subtypes, especially endometrioid adenocarcinoma. In all gynecologic cancers examined, there was no clear correlation between the telomerase activity and age at diagnosis or age of menopause. Although all tumors with 100 units or more telomerase activity were cancerous, the sensitivity was 39% in cervical cancer, 41% in endometrial cancer and 21% in ovarian cancer, respectively. Cervical intraepithelial neoplasia (CIN) had already increased telomerase activity and endometrial cancer with lymph node metastases had also greater activity than that without lymph node metastases. Although telomerase activity in ovarian cancer tended to increase as stage advances, it is noteworthy that clear cell adenocarcinoma showed significantly lower telomerase activity than endometrioid adenocarcinoma.