Familiar adenomatous polyposis (FAP) is a hereditary disease characterized by the development of multiple adenomatous polyps in the gastrointestinal tract and colorectal cancer in practically all patients who do not receive appropriate treatment. Although the most commonly involved region in this disease is the colorectal area, it is well known that adenomas can also develop in the upper gastrointestinal tract, mainly in the periampullary area of the duodenum. Because of the possibility of malignant transformation of these polyps, adequate monitoring is required, even though the optimal follow-up schedule has not yet been defined. In the present article, we report a case of a gastric adenocarcinoma detected during the follow-up of a patient diagnosed with FAP, as well as a review of the literature on this subject. We stress the need for early detection and appropriate management of this disease. Sufficient information is available to support the use of upper gastrointestinal endoscopy with lateral vision and serial biopsies of the periampullary region in these patients. The first endoscopy in patients with FAP should be performed at the age of 20 years or at diagnosis. Subsequently, a follow-up schedule should be designed, according to the number and histological characteristics of the polyps observed.