Postoperative agitation is a common problem after sevoflurane anesthesia in children. In the present study, we evaluated if tropisetron or clonidine could reduce the incidence of postoperative agitation after day case adenoidectomy in small children. We included 75 unpremedicated children aged 1–7 yr who were randomly assigned to receive either placebo, tropisetron (0.1 mg/kg) or clonidine (1.5 μg/kg) after anesthesia induction. Anesthesia was induced and maintained with sevoflurane. Patients also received alfentanil (20 μg/kg) and diclofenac (1 mg/kg). Postoperative pain was treated with IV oxycodone (0.05 mg/kg). Time to achieve discharge criteria was recorded. Modified pain/discomfort scale was used assess the postoperative behavior. The incidence of postoperative agitation was significantly less (32%, 8/25 patients) in the tropisetron group compared with placebo (62%, 16/26 patients), P < 0.05). Clonidine could not prevent agitation (incidence 54%, 13/24). No adverse effects were noted during the study. Discharge times were similar between the groups (between 80 and 99 min on average). In conclusion, tropisetron 0.1 mg/kg significantly reduced the incidence of postoperative agitation after sevoflurane anesthesia. Clonidine 1.5 μg/kg did not differ from placebo with respect to postoperative agitation.