This is a retrospective study determining the completeness and accuracy of processed information of emergency department (ED) records of a busy urban children's hospital. The method of study was based on comparing computer processed information with that in the patient's medical chart. A total of 457 ED visits from April 5 to April 25 of 1992 were audited. Accuracy was found to differ with the type of data element and the setting. Among admissions, admitting diagnoses coding had the highest error rate (53.1%), followed by age (33.2%), admitting time (31.0%), and admitting ward (12.5%). Among discharges, time in had the highest error rate (76.0%), followed by area where seen (56.9%), physician name (48.4%), time out (37.8%), age (33.3%), mode of arrival (26.2%), diagnosis (20.1%), patient's condition (17.3%), and triage level (10.7%). Despite advances in computerized information systems, error rates of processed information remain unacceptably high. Future information systems should be interactive, recording rather than processing information flows between the provider and the patient.