Clonidine is effective in treating sevoflurane-induced postanesthesia agitation in children. We conducted a study on 169 children to quantify the risk reduction of clonidine agitation in patients admitted to our day-surgery pediatric clinic. Children were randomly allocated to receive clonidine 2 mug/kg or placebo before general anesthesia with sevoflurane that was also supplemented with a regional or central block. An observer blinded to the anesthetic technique assessed recovery variables and the presence of agitation. Pain and discomfort scores were significantly decreased in the clonidine group; the incidence of agitation was reduced by 57% (P = 0.029) and the incidence of severe agitation by 67% (P = 0.064). Relative risks for developing agitation and severe agitation were 0.43 (95% confidence interval, 0.24-0.78) and 0.32 (0.09-1.17), respectively. Clonidine produces a substantial reduction in the risk of postsevoflurane agitation in children.