Objectives: To evaluate (1) the appropriateness of the after-hours referral (AHR), (2) clinical characteristics of urgently referred patients, and (3) parental compliance with disposition recommendations by the After-Hours Call Center of the Children's Hospital, Denver, Colo. Subjects:Patients of Denver, Colo, pediatricians who called after office hours were triaged by nurses using a computerized triage system, and were referred for afterhours evaluation to 1 of 5 urgent care sites (N = 409).Design: Data were collected at each site for 2-week periods every 3 months, from October 1996 to October 1997 (total study period, 10 weeks). Appropriateness of AHRs (diagnoses, clinical interventions, and final dispositions) were determined by a questionnaire that was completed by the evaluating physician. Parental compliance with the AHR was assessed by review of the after-hours site patient database and by telephone survey. Results:Of the referred patients, 339 (82.9%) complied with the recommendation for AHR and, of these, physician questionnaires were completed for 332 (97.9%). The mean percentage of evaluated patients judged appropriate was 90.7% and did not differ statistically by site or by physician training. A history indicating a potentially serious condition was the most common reason for judging a referral appropriate (80.1%), followed by patient discomfort (53.3%), findings from a physical examination (42.5%), parental anxiety (41.5%), and an urgent need for diagnostic test or therapy (34.7%). Of evaluated patients, 37.0% had a diagnostic test, and in 43.5% of cases, the evaluating physician thought a therapeutic intervention was necessary that night. Of the total sample, 93.4% were discharged and 6.6% were admitted to the hospital. The major reasons given by families for noncompliance were lack of understanding of the disposition recommendation and disagreement with the need for urgent referral.Conclusions: Approximately 90% of patients who complied with a referral for urgent evaluation by the AfterHours Call Center were judged by the evaluating physician to have been appropriately referred. The appropriateness rate for all referrals may be lower if there is significant self-selection in those families who do not comply.