This study is to determine if a locally applied immune response modifier will eliminate high grade dysplasia in Barrett's esophagus. Barrett's esophagus is a premalignant condition caused by chronic reflux of gastric contents into the lower esophagus. Present practice is to do a periodic esophagoscopy on patients with Barrett's esophagus and take biopsies in search of dysplasia. If the pathologist reports low grade dysplasia, the patient usually receives more intensive surveillance. If the pathologist reports high grade dysplasia, the patient and his physician are faced with a dilema. High grade dysplasia is carcinoma in situ and there is a strong propensity for such patients to progess to frank carcinoma of the esophagus. Carcinoma of the esophagus is a miserable disease which is difficult to treat and leads to death in about 95% of the cases at 5 years. The present standard for patients with high grade dysplasia is to recommend esophagectomy. Esophagectomy is a major surgical procedure with significant associated morbidity and mortality. Porfimer sodium(Photofrin) photodynamic therapy is effective in eliminating high grade dysplasia in Barrett's esophagus. It has been approved by the FDA but it is not widely utilized because of its complexity and expense. Other modalities such as endoscopic mucosal resection and endoscopic thermal ablation techiques are being studied. Although endoscopic techniques are much safer than surgery, they all are uncomfortable and carry some risk. Many patients with Barrett's esophagus are elderly and most with high grade dysplasia do not live long enough to develop cancer. This fact has made some gastroenterolgists recommend intensive surveillance as an alternative to the above mentioned therapeutic modalities. Intensive surveillance in this setting means endoscopy with biopsies every 3 months with specific therapy recommended only if frank cancer is found. This study is based upon the fact that intensive surveillance is an acceptable way of following these patients. The only difference is an oral agent will be added in hopes of getting rid of high grade dysplasia. If high grade dysplasia could be eliminated by an oral medication it would be a quantum improvement over what we have. The present belief is if high grade dysplasia is eliminated there would be no progression to cancer.