Background: The present study was performed with the aim of comparing the peak inspiratory pressure and lung dynamic compliance between a classic laryngeal mask airway (LMA) and an endotracheal tube in children under mechanical ventilation. Materials and Methods: In this study, 30 children aged 1 to 7 years with a physical condition of ASA I–II who were admitted for operations to repair inguinal hernias, hydroceles, or hypospadias were randomly enrolled. After induction of anesthesia, the appropriate laryngeal mask was used for each patient and they were placed under pressure-controlled mechanical ventilation. The peak inspiratory pressure was adjusted and recorded to obtain an appropriate tidal volume, then the laryngeal mask was removed and the appropriate size uncuffed endotracheal tube was inserted and the patient was placed again under controlled mechanical ventilation. The required settings were adjusted and peak inspiratory pressure and tidal volume were measured and recorded by the ventilator. Dynamic compliance was also calculated in both cases using the appropriate formula. Results: The results showed that peak inspiratory pressure (PIP) with the use of LMA in children under mechanical ventilation was less than the PIP with the use of an endotracheal tube (p0.05). Also, the pulmonary dynamic compliance with a laryngeal mask was greater than the use of an endotracheal tube (p0.05). Conclusion: A laryngeal mask airway due to its low airway resistance and high dynamic compliance is an acceptable alternative to a tracheal tube during mechanical ventilation and it can be a good alternative to the endotracheal tube, especially during mechanical ventilation of children, in whom avoidance of barotrauma is desirable.