In a longitudinal study, 21 patients with familial amyloidosis with polyneuropathy (FAP) were followed up for more than three years. Gastrointestinal symptoms ultimately evolved in all patients. In the advanced stage of the disease, 13 patients had diarrhea together with anal incontinence. Weight loss was very common and related to both malabsorption and motility disturbances with anorexia and also to muscular atrophy. Steatorrhea was found in 19 patients at least once during the follow-up. The duration of the disease was significantly correlated to fecal fat output. The conclusion was drawn that the gastrointestinal involvement in FAP is very common and of great clinical importance. The consequences of malnutrition also influence the outcome of the disease.