We observed the sequential development of columnar lined epithelium associated with adenocarcinoma, squamous dysplasia related with squamous cell carcinoma and adenosquamous carcinoma which were induced by duodeno-esophageal or gastro-duodeno-esophageal reflux in rats. Wistar male rats, weighing approximately 250 g were employed. Animals received total gastrectomy and were reconstructed with esophago-jejunostomy, which causes unavoidable duodeno-esophageal reflux. The animals were sacrificed every 10 weeks after surgery until 50 weeks. Erosions and basal cell hyperplasia were observed in the lower esophageal squamous epithelium at 10 weeks after surgery. At 20 weeks, glandular structures featured with galactose oxidase-Schiff-positive staining (foveolar metaplasia) appeared in the basal layer of esophageal squamous epithelium. At 30 weeks, the glands developed and formed cysts which were stained with concanavalin A (pyloric glandular metaplasia) or/and high iron diamine and alcian blue (intestinal metaplasia). Since 40 weeks after surgery, esophageal carcinomas were found. As adenocarcinomas were surrounded by the columnar-lined epithelium, squamous cell carcinoma and adenosquamous carcinoma were accompanied by squamous dysplasia. Persistent duodeno-esophageal reflux can change the stem cells of squamous epithelium to make columnar-lined cells. As part of the sequence of events leading to the development of columnar-lined epithelium, foveolar metaplasia was observed followed by the appearance of pyloric glandular metaplasia and intestinal metaplasia. Chronic duodenal reflux induces the development of esophageal carcinoma not only adenocarcinoma also squamous cell carcinoma and adenosquamous carcinoma. These pathways of carcinogenesis were different dual patterns.