In the last 7 years, 14 randomized controlled trials in patients with acute respiratory distress syndrome (ARDS) have shown that: • Mechanical ventilation with a tidal volume of 6 mL/kg of predicted body weight is better than mechanical ventilation with a tidal volume of 12 mL/kg of predicted body weight. • Prone positioning improves oxygenation but poses safety concerns. • A high level of positive end-expiratory pressure does not improve survival. • High-frequency oscillatory ventilation is in theory the ideal "lung-protective" method, but its benefits have not been proven. • No drug therapy has been shown to improve survival in patients with ARDS. • Exogenous surfactant may improve oxygenation but has no significant effect on the death rate or length of use of mechanical ventilation. • Low-dose inhaled nitric oxide has no substantial impact on the duration of ventilatory support or on the death rate. • Partial liquid ventilation may be beneficial in young patients with acute lung injury or ARDS, although further study is needed to confirm this.