OBJECTIVES: This report describes ambulatory care visits to hospital outpatient departments (OPDs) in the United States. Statistics are presented on selected hospital, patient, and visit characteristics. Selected trends in OPD utilization from 1995 to 2005 are also presented.METHODS: The data presented in this report were collected in the 2005 National Hospital Ambulatory Medical Care Survey (NHAMCS), a national probability sample survey of visits to emergency and OPDs of nonfederal, short-stay, and general hospitals in the United States. Sample data are weighted to produce annual national estimates.RESULTS: During 2005, an estimated 90.4 million visits were made to hospital OPDs in the United States, about 31.0 visits per 100 persons. Fema...