The effects of ethanol upon the gastrointestinal tract (mouth, pharynx, esophagus, stomach, duodenum, Oddi's sphincter, small bowel, colon and rectum) were reviewed. Several studies showed that the incidence of cancer in the mouth and pharynx is increased in alcoholics as a consequence of ethanol effects and probably those of other compounds found in liquors. The gastroesophageal reflux disease may be induced by alcohol since it reduces the pressure in the lower and the upper esophageal sphincter, as well as the extent of primary peristalsis. Several studies showed a strong correlation between esophageal cancer and alcohol abuse. The risk for developing this kind of tumour is significantly increased when alcohol abuse and smoking coexist. Alcoholism predisposes patients to Mallory-Weiss syndrome as well as to bleeding of esophageal varices Ethanol may affect gastric secretion, motility, and permeability. Some drugs acting upon the gastric alcohol-dehydrogenase are able to affect gastric absorption of ethanol. Eradication of Helicobacter pylori increases the activity of alcohol-dehydrogenase in the pyloric antrum. The effects of alcohol upon the gastric mucosa include caustic damage, retrograde diffusion of H+, and cytoprotection. This agent may cause an acute gastritis but it is probably not involved in chronic gastritis. Whether alcohol is a risk factor for ulcer or not is unknown. Some studies found an increased incidence of gastric cancer associated with consumption of beer, wine and vodka. Some authors reported a decreased pressure in Oddi's sphincter while others found it increased in association with the consumption of ethanol. The acute and the chronic consumption of alcohol may affect the structure of small bowel as well as the absorption of nutrients. Several studies reported a significant correlation between colorectal cancer and the chronic consumption of ethanol.