During a 12-month period ending on 11/30/88, data were collected on 16,010 pediatric patients who visited a pediatric emergency department (ED). These ED patients prospectively fell into one of the target areas for further study, including wheezing (15%), trauma (excluding burns; 29%), burns (1%), water-related injuries (1%), ingestions and toxic substance exposures (2%), child abuse (3%), handicapping conditions (5%), preventable incidents (33%), and ambulance arrivals (7%). Handicapped patients were more likely to require an ambulance. Younger patients, males, and patients with handicaps, wheezing, and Medicaid insurance were more likely to visit the ED on multiple occasions. Primary care physicians could be identified in 77% of the cohort. Large-scale interventions to reduce preventable pediatric morbidity and mortality have suffered from difficulties in documenting their effect in a population-based sample. A statewide pediatric emergency encounter registry is proposed.