Barrett's esophageal adenocarcinoma (BEAC) arises from Barrett's esophagus (BE), a premalignant lesion caused by acid reflux (heartburn). Although the cancer is uncommon, its incidence is rapidly rising in western countries. Like most other cancers, BEAC cells also have elevated telomerase activity which maintains telomere length and supports continued proliferation of these cells. It is not clear if telomerase is activated early at premalignant (BE) stage, because reports of telomerase activity in Barrett's and normal esophagi have been controversial. We have shown that detection of telomerase and telomeres becomes easier and much more reliable if purified BE cells are used instead of tissue specimens. This chapter, therefore, emphasizes the importance of laser capture microdissection and provides the method to purify Barrett's esophagus related cells, using this technique.