Villous adenoma of the duodenum is rare and has a high prevalence of cancer. We report here an unusual case of a 73-year-old man who presented with a tumour on the second part of the duodenum with moderate dysplasia of a tubulo-villous adenoma at the biopsies. A segmental duodeno-jejunal resection was performed and the resection margins were negative. The final histological analysis was a moderately differentiated invasive duodenal adenocarcinoma (pT3Nx). Management of these tumours is discussed here.