The purpose of our study was to show the effects of laparoscopic procedures on the ventilation of children. We measured an increase of ventilation pressures (Pmax, Ppfat and Pmean) of 28, 35 and 48% respectively. petCO2 rose from 35 to 41 +/- 2 mmHg. There was no loss of body temperature in any child. Laparoscopic procedures as seen here for appendectomy or diagnostic exploration in children of 13.5 kg body weight or more caused no problems that were clinically evident. The increase of ventilation pressure could be attenuated by choosing the parameters of ventilation (e.g. flow, I:E ratio) in such a way that Pmax does not exceed 20 mbar. Alternatively, pressure-controlled ventilation may be used, adjusting petCO2 by ventilation frequency. In any case there must be a strict control of all possible side effects of laparoscopy, such as cutaneous emphysema or pneumothorax.