PURPOSE: Telomeres are specialized structures containing unique (TTAGGGG) repeats at the ends of eukaryotic chromosomes that are thought to be important in the protection and replication of chro mosomes. Lagging strand DNA synthesis at the end of linear chromosomes cannot be complieted (referred to as the end-replication problem), and this results in the progressive shortening of telomeric repeats with each cell division. This shortening of telomeres has been proposed as the mitotic clock, and when telomeres are sufficiently short, may contribute to replicative cellular senescence in cells. The enzyme telomerase permits the de novo synthesis of telomeric DNA into chromosomal ends. Apoptosis is physiologic cell death and prevent cancerous transformation of cell. METHODS: We measured the telome rase activity with the use of a PCR-based telomerase assay and apoptosis, in 10 superficial gastritis and 13 gastric cancer patients. RESULTS: Telomerase activity was present in 70% of the gastric cancer patient and in 92.7% of the superficial gastritis patients (P=0.171). Apoptosis was present in 0% of the gastric cancer patients, and in 80% of the superficial gastritis patients (P=0.001). CONCLUSION: Telomerase activity was detected in and cancer and inflammatory tissue. Although there is progressive cellular division due to telomerase activity, cancerous transformations are prevented by apoptosis.