OBJECTIVE This report presents data on the provision and utilization of ambulatory medical care services in hospital emergency departments during 1992. Ambulatory medical care services are described in terms of patient, visit, and facility characteristics. Among these are the patient's reason for the visit, diagnostic and screening services ordered or provided, diagnosis, and medications provided or prescribed. Cause of injury data are presented for injury-related visits. METHODS Data presented in this report are from the 1992 National Hospital Ambulatory Medical Care Survey (NHAMCS), a national survey of non-Federal, general and short-stay hospitals, conducted by the Division of Health Care Statistics, National Center for Health Statistics, Centers for Disease Control and Prevention. This report reflects the survey's first year of data collection. A four-stage probability sample design was used, resulting in a sample of 524 non-Federal, general and short-stay hospitals. Ninety-two percent of eligible facilities participated in the survey. Hospital staff were asked to complete Patient Record forms for a systematic random sample of patient visits occurring during a randomly assigned 4-week reporting period, and 36,271 forms were completed by participating emergency departments. Diagnosis and cause of injury were coded according to the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM). Reason for visit and medications were coded according to systems developed by the National Center for Health Statistics. RESULTS An estimated 89.8 million visits were made to the emergency departments of non-Federal, general and short-stay hospitals in the United States during 1992-357.1 visits per 1,000 persons. Persons 75 years of age and over had a higher visit rate than persons in five other age categories. White persons accounted for 78.5 percent of all visits. However, the visit rate for black persons was significantly higher than for white persons overall and for every age category except 65-74 years and 75 years and over. More than half of all visits were illness related and more than one-third were injury related. Stomach and abdominal pain and chest pain were the most frequently mentioned reasons for visiting the emergency department, accounting for about five million visits each, or 10.7 percent of the total. Accidental falls accounted for the largest share of injury-related visits (22.7 percent).