Each year in the United States, an estimated 76 million persons experience foodborne illnesses. CDC's Emerging Infections Program Foodborne Diseases Active Surveillance Network (FoodNet) collects data on nine foodborne diseases in selected U.S. sites to quantify and monitor foodborne illnesses. This report describes preliminary surveillance data for 1999 and compares them with data from 1996-1998. The data suggest that the incidence of the foodborne illnesses under surveillance declined during 1999 compared with 1996 primarily as a result of decreases in campylobacteriosis and shigellosis and indicate substantial regional variation in the incidence of foodborne diseases.