BACKGROUND/AIMS: Telomerase activity and telomerase reverse transcriptase (TERT) expression have been proposed as a marker for malignancy. However, little is known about those markers in intestinal metaplasia (IM). This study was performed to evaluate the usefulness of telomerase activity in gastric washing fluid and TERT expression in tissue as a marker for early diagnosis of stomach cancer. METHODS: Gastric washing fluid and biopsies were taken endoscopically. We examined the telomerase activity by telomeric repeat amplification protocol (TRAP) and the TERT expression by semiquantitative reverse transcription-polymerase chain reaction in 26, 21 and 15 cases of cancer, IM, and normal mucosa respectively. RESULTS: The telomerase activity was positive in 65% of cancer, 44% of incomplete IM, and 33% of complete IM. The TERT was expressed in 89% of cancer, 81% of IM, but not in normal mucosa. The TERT expression level was higher in cancer and incomplete IM than in complete IM and normal mucosa (p<0.05). CONCLUSIONS: Telomerase activity in gastric washing fluid and TERT expression in tissue may have limited usefulness as a marker for the early diagnosis of stomach cancer. However, the increased levels of TERT expression in IM and cancer suggest that TERT expression may be associated with carcinogenesis in stomach cancer.