The authors identified 132 patients who died with a documented diagnosis of familial adenomatous polyposis (FAP). A review of the medical records, autopsy reports, and in-depth discussion with local physicians and well-informed family members was performed. It was impossible, even after the review, to ascertain the exact cause of death in 22 patients. In the remaining patients, the cause of death was as follows: metastatic colorectal carcinoma, 64 patients (58.2 percent), (colon, 49 [44.5 percent], rectal, 15 [13.6 percent]); desmoid tumors, 12 (10.9 percent); periampullary carcinoma, 9 (8.2 percent); brain tumors, 8 (7.3 percent); perioperative mortalities, 5 (4.5 percent); adrenal carcinoma, 1 (0.9 percent); and abdominal carcinomatosis, 1 (0.9 percent). Ten patients died of causes not related to FAP. The major causes of death in 36 patients who underwent prophylactic colectomy were desmoid tumor and periampullary malignancy. This finding underscores the importance of lifelong surveillance and periodic endoscopic evaluation in patients with FAP.