The acute respiratory distress syndrome (ARDS) was first described by Ashbaugh and colleagues in 1967. However, despite considerable efforts, early progress in treatment was slowed by lack of consistent definitions and appropriately powered clinical trials. In 1994, the American-European Consensus Conference on ARDS established criteria defining ARDS as well as acute lung injury (ALI). Additionally, the conference established research directives and international coordination of clinical studies. Current incidence of ALI in the United States is estimated at 200,000 cases per year with a mortality rate approaching 40%. Mechanical ventilation, using positive end-expiratory pressure and reduced tidal volumes and inspiratory pressures, along with improved supportive care has increased survival rates. However, to date, pharmacological therapies have failed to improve survival in multicenter clinical trials. This article focuses on clinical treatments for ALI that have been tested in phase II and III clinical trials as well as a discussion of potential future therapies.