Abstract: A method and apparatus to treat Barrett's tissue, a pre-cancerous condition, by removing the epithelium above the lower esophageal sphincter through cryo-ablation. An endoscope with fiber optics is used to view the operation, and a catheter for supplying liquid nitrogen is passed through the lumen of the endoscope. Liquid nitrogen is sprayed directly onto the Barrett's tissue through the catheter while the physician views the operation through the fiberoptics of the endoscope and controls the spray via a valve. Freezing is indicated by whiteness and shows that the epithelium has been cryoablated. The apparatus can also be used to treat various other gastrointestinal tract lesions. A most important and significant feature of this invention is the fact that the liquid nitrogen spray is applied in the esophagus at low pressure.