BACKGROUND: The eradication of early stage neoplastic lesions in Barrett's esophagus is imperative to prevent invasive adenocarcinoma. Early stage lesions have an extremely low risk of lymph node metastasis, thereby, making local treatment feasible. Photodynamic therapy destroys malignant cells by a photochemical effect. The aims of this study were to evaluate the efficacy and tolerance of photodynamic therapy with green light and a new photosensitizer, temoporfin or m-tetrahydroxyphenyl chlorin in patients with Barrett's esophagus and early stage neoplastic lesions. METHODS: Four days after injection of m-tetrahydroxyphenyl chlorin, lesions were illuminated at a wavelength of 514 nm through non-circumferential windowed diffusers. Follow-up endoscopy with biopsies was performed at regular intervals. RESULTS: Fourteen lesions (7 high-grade dysplasia, 7 intramucosal adenocarcinoma) in 12 patients were treated. For all lesions, efficacy was 100% and squamous re-epithelialization was complete. Side effects were of moderate severity (one stricture). Mean follow-up was 34 (15) months (range 12-68 months). CONCLUSIONS: Green light photodynamic therapy with m-tetrahydroxyphenyl chlorin can eradicate early stage neoplastic lesions in Barrett's esophagus and may be proposed as an alternative first-line therapy or a second-line therapy after failure of other endoscopic treatments. The efficacy and patient tolerance of the procedure justify further studies of the method in larger groups of patients.