An 82-year-old man, suffering abscess secondary to femoral prosthesis replacement, complained of intractable watery diarrhea and melena. Autopsy disclosed 12 mm-sized perforation at the gastric prepylorus and purulent peritonitis. Amyloid A was deposited in systemic organs and tissues, including the site of gastric perforation. IgM was co-deposited in the glomeruli.