AIM To study the expression of telomerase activity in malignant esophageal neoplasms and normal humanesophageal epithelia.METHODS Telomerase activity was assayed by the telomere repeat amplification protocol (TRAP)method. All the neoplasms and epithelia of esophagus were confirmed by routine pathological diagnosis.RESULTS Telomerase activity was assayed in 18 normal esophageal epithelial tissues and in 35 malignantneoplasms of esophagus, including 27 cases of esophageal carcinoma and 8 cases of cardiac carcinoma.Telomerase activity was detected in most of malignant neoplasms of esophagus (91.4%, 32/35) and in allthe normal esophageal epithelial tissues except one (18/19).CONCLUSION The results suggest that in addition to contributing to proliferation of immortal blast cellsand neoplastic cells, telomerase activity may also play a similar role in regeneration of normal epithelia ofhuman esophagus. The potential use of telomerase activity as a diagnostic marker in human esophagealneoplasm might not be suitable.