['Duodenal cancer and ampullary cancer are major causes of death after a prophylactic colectomy in patients with familial adenomatous polyposis (FAP). Forward-viewing endoscopy and side-viewing endoscopy are recommended in patients with FAP for surveillance of periampullary and duodenal polyposis. The study of polyps distal to the duodenum in FAP is limited. A capsule endoscopy (CE) allows visualization of the mucosa of the entire small bowel.', 'The objective was to detect whether CE has clinical value or any utility for the surveillance of small-bowel polyps in patients with FAP and to evaluate whether there are genotypic factors that predict which patients are at a lower risk of small-bowel polyps.', 'Two Italian tertiary-referral centers.', 'Twenty-three patients with FAP who presented for a CE.', 'Patients with FAP were examined by CE to assess the location, size, and number of small-bowel polyps. Patient age at CE, sex, years of observation after surgery, type of surgery, duodenal adenomas, and colorectal cancer at surgery were analyzed. All patients were selected for mutation analysis, and the germline adenomatous polyposis coli (APC) gene mutation was detected.', 'Eleven of 23 patients with FAP had duodenal polyps. During CE, jejunal-ileal polyps were detected in 7 of 23 FAPs, with a total number of 15 polyps in the ileum. The presence of duodenal adenomas was the only clinical feature predictive of small-bowel polyps. Identification of the ampulla of Vater was not achieved with CE; duodenal polyps were only seen in 4 of 11 patients identified endoscopically, with an underestimation of polyp numbers. APC mutations between codons 499 and 805 were associated with the absence of small-bowel polyps.'] Is capsule endoscopy useful and safe for small-bowel surveillance in familial adenomatous polyposis?