BACKGROUNDs: It is widely known that desflurane provides fast emergence but with a high incidence of emergence agitation. This study was designed to investigate the emergence agitation resulting from thiopental or ketamine induction with desflurane anesthesia for pediatric patients. METHODS: Forty patients, aged 3-8 years, scheduled for a tonsillectomy or a tonsillectomy and adenoidectomy were randomly allocated into two groups. Anesthesia was induced using 5 mg/kg thiopental sodium (Group T patients) or 2 mg/kg ketamine (Group K patients), and was maintained using O2-N2O-desflurane. The recovery time and incidence of emergence agitation were assessed. RESULTS: The incidence of emergence agitation was less in patients in the ketamine induction group. There were no differences in the recovery time and reported side effects. CONCLUSIONS: We conclude that ketamine induction provides less emergence agitation when compared to thiopental induction for desflurane anesthesia for a pediatric tonsillectomy or a tonsillectomy and adenoidectomy without delayed recovery.