Knowledge of the spectrum and relative frequencies of pediatric emergencies is an important factor in developing appropriate training curricula for physicians treating children in emergency departments. To provide these data, we reviewed the records for four one-week periods (January, April, July, and October) of a large pediatric emergency department to describe the population in terms of age, chief complaints, diagnoses, time of arrival, seasonal variation, and disposition. There were 3796 log entries. Complete information on all variables was obtained on 3784 patients. Age ranged from one day to 39 years, and the mean age was 6.0 +/- 6.15 years. One half of all emergency department visits were by children three years old or younger. On the other hand, 12% of visits were by adolescents (ages 13 to 18), and one in 25 visits was made by an adult (greater than 18 years old). The majority of chief complaints and final diagnoses were related to infection and trauma. More than half of the patients arrived on the evening shift, between 4 pm and 12 am. Eleven percent of the children seen on day and evening shifts and 13% from the night shift were admitted. From the analysis of our data we recommend expanded skills in the management of minor trauma for pediatric residents, an emphasis on management of infections for nonpediatric emergency specialists, and extensive training in both pediatric and adult trauma for physicians in pediatric emergency medicine fellowships.