The pathology of the alimentary tracts of nine patients dying of Salmonella typhimurium infection is reviewed. Two patients had previous gastric operations, supporting previous reports that such patients are more susceptible to food poisoning. Four had no parietal (oxyntic) cells in the gastric mucosa, suggesting hypo- or anacidity. Only one had acute gastritis. None had acute enteritis, but in half of the patients, subtle histological changes suggested an 'enteropathy'. Acute diffuse colitis with abundant crypt abscesses, without stromal abscesses in the lamina propria, was the most constant finding and reparative features started very early, and occurred in later deaths. Under ideal circumstances this crypt abscess is readily distinguished from that of idiopathic ulcerative colitis, but can be confused with the crypt abscess of acute bacillary (sonne) dysentery. While the florid colonic changes may have settled in the late deaths, active inflammation is commonly present in the appendix mucosa on histology. The pathology of the alimentary tract in S typhimurium infection differs from that of S typhi and S paratyphi infections. There is little evidence of gastroenteritis, although subtle changes occur in the stomach and small intestine. The features are those of acute diffuse colitis with histological appendicitis, distinguishable from idiopathic ulcerative colitis.