Gastrointestinal infections are common and important in infants and young children, particularly where poor hygiene and living conditions allow the spread of infectious agents. With increasing information about microorganisms that cause these infections and improved methods to detect them, many episodes that were once undiagnosed can now be attributed to previously unrecognized viruses, bacteria, and other pathogens. These advances facilitate better management and will permit more effective control and preventive strategies. This review highlights some recent reports about enterovirulent classes of Escherichia coli, including E. coli O157:H7, which causes the hemolytic-uremic syndrome and hemorrhagic colitis; Campylobacter species and a new Campylobacter-like organism (Arcobacter butzleri); Helicobacter pylori; Aeromonas species; and rotavirus. Important new information about intestinal parasites, including Giardia and Cryptosporidium, has emerged that should prove of practical use in diagnosis and management in places where these parasites are prevalent in children, particularly in parts of the world where HIV infection has become established. A newly described organism, so far called coccidian-like or cyanobacterium-like body, has been found in patients with prolonged diarrhea (including travelers and expatriate residents) in several countries; the name Cyclospora cayetanensis has been proposed for this organism. This year's review concludes with a short commentary on some recent reports about risk factors that predispose children to gastrointestinal infections, eg, nutritional status, domestic hygiene, maternal hygiene behavior, and young children gathered in communal facilities like day care centers. Immune function status is also important, and deficiencies of single nutrients such as vitamin A, pyridoxine, folic acid, iron, and zinc may also play a role.