BACKGROUND: Low flow anesthesia provides many advantages, including reduced cost, conservation of body heat and airway humidity. This study was performed to compare low flow anesthesia with high flow anesthesia and to investigate whether the advantages of low flow anesthesia during positive pressure ventilation can be combined with the laryngeal mask airway in paralyzed pediatric patients. METHODS: Thirty-one pediatric patients of ASA physical status 1 or 2 were studied and divided into two groups according to the fresh gas flow (FGF) in the breathing system; low flow group (FGF approximation 1 L/min, n = 17) or high flow group (FGF approximation 4 L/min, n = 14). Each respiratory parameter was measured when a steady state was reached at 20 min after induction. RESULTS: There were no significant differences of respiratory data between the two groups except that the inspired oxygen concentration was lower in the low flow group than in the high flow group. Hemodynamic changes with the laryngeal mask airway insertion were not statistically significant. CONCLUSIONS: A laryngeal mask airway is an effective airway device for low flow anesthesia as well as for high flow anesthesia in paralyzed pediatric patients.