We studied the safety of positive pressure ventilation (PPV) when using the size 2 laryngeal mask airway (LMA) in 46 ASA physical status I or II children (aged 38 +/- 21 mo) undergoing elective surgery. The LMA cuff was inflated in incremental steps to achieve a cuff leak pressure greater than or equal to 15 cm H2O. Abdominal circumference was measured before and after PPV in study patients, as well as in a control group managed with tracheal intubation. Cuff leak pressure was 17 +/- 4 cm H2O (range 12-34 cm H2O). Forty-five patients successfully underwent PPV. Gas leak around the LMA cuff prevented PPV in one infant. The only respiratory variable that changed significantly was end-tidal CO2, which decreased from 40 +/- 6 to 34 +/- 5 mm Hg. Abdominal circumference increased in 28 patients but was not associated with any complications. Change in abdominal circumference in the study group was not significantly different from that observed in the control group. However, abdominal circumference increased 8 cm in one study patient, prompting insertion of an orogastric tube. The size 2 LMA provides an effective airway for PPV. Mild gastric distention often occurs. The risk of clinically significant gastric distention appears to be small, but it warrants close monitoring. We conclude that with certain precautions described in the text, the size 2 LMA provides a relatively safe airway for PPV in children.