The purpose of managing acute respiratory distress syndrome (ARDS) is "to open a closed lung" by increasing the airway pressure or changing the patient's position. Assessment of recruitment of atelectatic lung regions is necessary to have a correct management of mechanical ventilation and to be sure of positive end-expiratory pressure or prone position efficacy before their application. In fact, both of them could have collateral effects. Sonographic approach allows a dynamic evaluation of lung recruitment in patients affected by ARDS and it is easy to perform bedside. In particular, it is useful for patients too unstable to be moved to the CT room. Sonography is fast, cheap, and radiation free; thus, it can be repeated in order to monitor the evolution of ARDS. To our knowledge, the use of this technique in the setting of ARDS was never reported before.