Alterations in pulmonary surfactant is an important contributing factor in the pathogenesis of ARDS. Surfactant deficiency affects the progression and prognosis of ARDS patients and increases the susceptibility of ARDS in patients who are at risk for it. Several studies have suggested that the use of exogenous surfactant preparations can improve lung function and overall outcome in ARDS patients; however, large randomized clinical trials have failed to show any benefit. Continued work on surfactant therapy-including efforts to improve the mode of delivery, to understand better the pathophysiology of exogenous surfactant, and to develop synthetic surfactants that emulate natural ones more closely-will help to elucidate its role in ARDS.