摘要： Photodynamic therapy (PDT) is a technique developed in 1990 for reducing the severity of tumor symptoms and cancer size. It acts through a non-thermal mechanism utilizing the activation of a photosensitizer—administrated by intravenous, topical, or oral route—with a specific wavelength of light. The excited photosensitizer generates oxygen radicals which induces localized necrosis and cellular damage in the site of photoactivation. Site and depth of injury depended on several factors, including oxygen concentration, type of sensitizing agent, waiting time between dosing and light stimulation, energy per unit area, intensity of light dosimetry, wavelength, and time of irradiation. PDT may be used in the tissues accessible to light exposure, such as skin, retina, bronchial tree, and the gastrointestinal tract, for either palliative approach (namely lumen obstruction by lung and esophageal tract cancer) or curative therapy. In the gastrointestinal tract, PDT is thought to be effective in the treatment of Barrett’s esophagus with high-grade dysplasia. Further investigational applications include palliative approach to unresectable cholangiocarcinoma and treatment of duodenal or colon adenomas associated to FAP syndrome. Finally, there are few data on ablation of gastric superficial tumors. This review focused on PDT tools, indications, limits, and contraindications in the treatment of Barrett’s esophagus.