Introduction. The objective of this study was to evaluate Ki-67 antigen expression in patients with Barrett’s esophagus and esophageal adenocarcinoma and to assess its correlation with the metaplasia-esophageal adenocarcinoma progression.Methods. Using immunohistochemistry we evaluated the Ki-67 index in patients with Barrett’s esophagus, esophageal adenocarcinoma, and controls. We included patients with endoscopically visible columnar mucosa of the distal esophagus (whose biopsies revealed specialized intestinal-type metaplasia), patients with esophageal and esophagogastric tumors types I and II, and patients with histologically normal gastric mucosa (control).Results. In the 57 patients studied there were no statistically significant differences between the groups with respect to age or race. Patients with cancer were predominantly men. The Ki-67 index averaged10±4% in patients with normal gastric mucosa (n=17),21±15% in patients with Barrett’s esophagus (n=21), and38±16% in patients with cancer (n=19). Ki-67 expression was significantly different between all groups (P<0.05). There was a strong linear correlation between Ki-67 expression and the metaplasia-adenocarcinoma sequence (P<0.01). In patients with cancer, Ki-67 was not associated with clinical or surgical staging.Conclusions. Ki-67 antigen has increased expression along the metaplasia-adenocarcinoma sequence. There is a strong linear correlation between Ki-67 proliferative activity and Barrett’s carcinogenesis.