To evaluate the pattern and reasons for nonurgent use of the pediatric emergency department (PED) during regular office hours and why primary care physicians (PCP) approve such visits. Prospective, cross-sectional, observational study. Free-standing, university-affiliated children's hospital emergency department. Patients presenting to the PED and triaged as nonurgent between June and November 1994, Monday through Friday from 6:30 am to 6:30 pin, and Saturday 6:30 am to 12:00 noon. Registration and triage information and all communication with the PCP. Of 1020 eligible patients, 364 patients and their PCP completed the study. Fifty-two percent of the study patients were enrolled in a health maintenance organization (HMO). This is consistent with the penetration of managed care in this community. Most HMO (118 of 191, 62%) and non-HMO enrollees (147 of 173, 86%) did not call their PCP prior to arrival in the PED. Comparing the reasons given by these patients (HMO enrollees versus non-HMO) for not calling, we found: convenience (HMO 17% vs non-HMO 4%, P P Communication between the patient and PCP prior to the PED visit is poor in the study population. Convenience and physician workload appear to be important factors in the choice to use the PED for nonurgent problems.