Adenomas of the duodenum have been described in patients with familial adenomatous polyposis (FAP). Patients with FAP are at high risk for the development of periampullary cancer. The aim of our study was to evaluate if endoscopic visualization of small polyps, often overlooked at standard endoscopic examination, was improved by chromoendoscopy. Ten patients with FAP and previous colectomy underwent upper gastrointestinal endoscopy. Two skilled endoscopists were involved for each endoscopy. Evaluation of number and diameter of polyps was made before and after staining. After staining we detected a larger number of duodenal polyps than found at the standard endoscopic examination, the difference being statistically significant. This result seems to suggest that chromoendoscopy may improve diagnostic yield of endoscopy. Further studies are needed to suggest the best surveillance program and the appropriate therapeutic modality for these patients.