Infection with Campylobacter jejuni is one of the most common causes of gastroenteritis worldwide; it occurs more frequently than do infections caused by Salmonella species, Shigella species, or Escherichia coli O157:H7. In developed countries, the incidence of Campylobacter jejuni infections peaks during infancy and again during early adulthood. Most infections are acquired by the consumption and handling of poultry. A typical case is characterized by diarrhea, fever, and abdominal cramps. Obtaining cultures of the organism from stool samples remains the best way to diagnose this infection. An alarming recent trend is the rapid emergence of antimicrobial agent--resistant Campylobacter strains all over the world. Use of antibiotics in animals used for food has accelerated this trend. It is fortunate that complications of C. jejuni infections are rare, and most patients do not require antibiotics. Guillain-Barré syndrome is now recognized as a post-infectious complication of C. jejuni infection, but its incidence is <1 per 1000 infections. Careful food preparation and cooking practices may prevent some Campylobacter infections.