Résumé : BACKGROUND: Eradication of Barrett's mucosa by thermal or photoablation combined with high doses of proton pump inhibitors is a potentially attractive strategy in the management of this preneoplastic condition. However, major concerns of this method are the persistence of residual metaplastic glands beneath the new squamous epithelium and the absence of any knowledge of its impact on long term outcome. CASE REPORT: The case of an intramucosal adenocarcinoma diagnosed 18 months after apparently complete squamous re-epithelialisation achieved using argon plasma coagulation and high dose omeprazole (40 mg/daily) is reported in a 68 year old patient presenting initially with a Barrett's oesophagus without dysplasia. Intramucosal adenocarcinoma was located under the new squamous layer and presented as a bulging area covered by the squamous epithelium. It probably originates from residual metaplastic glands after therapy although a pre-existing tumour cannot be definitely excluded. CONCLUSION: This observation might question future application of this experimental endotherapy in non-dysplastic Barrett's oesophagus. It suggests that the residual glands might still be premalignant and that the early diagnosis of neoplastic changes might be compromised by the squamous re-epithelialisation.