Familial adenomatous polyposis (FAP) is a rare autosomal dominant precancerous condition of the colon caused by mutations in the adenomatous polyposis coli (APC) tumor suppressor gene. FAP is characterized by the appearance of innumerable adenomatous polyps throughout the large bowel. Fundic gland polyps are the most common gastric lesion in FAP. It is generally believed that fundic gland polyps have little or no potential for malignant transformation in the population at large, and only a few case reports describe the development of high grade dysplasia or gastric adenocarcinoma associated with diffuse fundic gland polyposis in patients with FAP. We report the second case of gastric adenocarcinoma intimately associated with fundic gland polyposis in a family with an attenuated form of FAP. The patient had undergone routine screening per current guidelines because of his known mutation in the APC gene. This suggests that malignant transformation of fundic gland polyps in patients with FAP occur more frequently than previously believed. Current screening recommendations may not be sufficient for patients with FAP or its attenuated forms.