OBJECTIVE To investigate the minimum alveolar concentration (MAC) of sevoflurane required for insertion of laryngeal mask airway (LMA) in anesthetized children. METHODS 27 children, aged 3-8, with an ASA physical status I or II, underwent elective surgery under general anesthesia induced by inhalation of 8% sevoflurane in oxygen. After loss of eyelash reflex, the designated end-tidal concentration of sevoflurane remained stable for at least 10 min, and then the LMA was inserted. Each target concentration at the time of insertion was predetermined by the Dixon up-and-down method (with 0.2% as a step size) starting at 2.0% end-tidal concentration of sevoflurane. Successful insertion was defined as excellent inserting condition (fully relaxed jaw, no coughing, and no movement of the limbs, no breath holding, and no laryngospasm). RESULTS The mean MAC of sevoflurane to achieve successful LMA insertion in 50% of children was (2.01 +/- 0.19)%, and the ED(95) was 2.36% (95% CI 2.15% - 4.15%). CONCLUSIONS LMA insertion can be safely accomplished without coughing, moving, or any other airway complications in 50% and 95% of children at 2.01% and 2.36% end-tidal concentrations of sevoflurane.