Abstract: Objective To detect the expression of telomerase with TRA P PCR ELISA indirect quantitative method in nasopharyngeal carcinoma(NPC). Methods Telomerase activity was detected in 18 cases of NPC,4 cases of the epithelium adjacent to NPC and 4 cases of chronic nasopharyngitis with TRAP PCR ELISA indirect quantitative method.At the same time,the activity of telomerase i n 22 HNE1 cell strains,5 cases of Leukemia marrow cells,2 cases of normal mar row cells and 6 vasculor smooth muscle cell strains as well as in the HNE1 cel l strains of different concentration and NPC after hot inactivating was also exp lored. Results The telomerase activity in NPC and the epithelium adja cent to NPC reached at 1.03±0.88U and 1.0±0.59U respectively compared wit h 0.16±0.06U in chronic nasopharyngitis (P＜0.01).There also was a high er telomerase activity in HNE1 cell strains and leukemia marrow cells than in normal marrow cells and vascular smooth muscle cell strains (P＜0.01).Exp eriments showed that the telomerase activity of NPC after hot inactivating was l ost and detection of the telomerase activity could also be got at a concentratio n as small as 1×102HNE1 cells/ml. Conclusion There is a high te lomerase activity in NPC in vivo and in vitro.TRAP PCR ELISA indirect quantitati ve assay has many advantages such as high sensitivity,specificity and reliabilit y and is able to reveal and compare different activity status of the telomerase.