We found degeneration of enteric nerve plexuses in two patients with type I familial amyloid polyneuropathy. Amyloid deposition was more severe in the wall of the stomach than in the rectum. Hypomotility of the upper gastrointestinal tract, resulting from both amyloid deposition in the stomach and upper bowel and degeneration of the intrinsic autonomic nerves, may be responsible for anorexia, nausea, and vomiting. Diarrhea and constipation may be caused by degeneration of the enteric nerve plexuses. Gastric biopsy is valuable and safe in the diagnosis to type I familial amyloid polyneuropathy.