Since the first description of acute respiratory distress syndrome (ARDS) as a series of 12 patients in 1967 by Ashbaugh et al.1 , it still remains a major public health problem that incurs high health care costs and causes major mortality in the intensive care unit (ICU) despite improvements in outcomes in the last two decades. ARDS refers to the occurrence of severe hypoxemia that was not corrected by oxygen treatment and is characterized by heterogeneous acute lung inflammation with increased permeability of the alveolar-capillary membrane, resulting in the development of exudate within the alveolar space, damage due to activated neutrophils and cytokines, and abnormalities of surfactant and the coagulation system2 . The definition also recently changes as the Berlin criteria3 , which was modified to the original American-European Consensus Conference definitions4 and novel clinical trial designs in ARDS may anticipate a new era of successful therapies. Although over the past decades, there has been a remarkable development in the therapeutic approach and management of critically ill patients with ARDS, the mortality of patients with ARDS is unacceptably high, up to 40%5 . In Korea, it has been reported that 79 patients with ARDS were admitted to the ICUs of 28 university hospitals all over the country within 1 month, July 2009, and 45 of those patients died, resulting in a mortality rate of 57%6 . Also, until now there is no wellstated clinical practice guideline for intensivists about ARDS, especially focused on the critical care including applying mechanical ventilation until now. Herein, we report the recommendations and suggestions of how to manage mechanically ventilated patients with or without ARDS