Acute lung injury is defined as inadequate oxygenation of the blood due to primary and secondary injuries of the lungs that limit normal gas exchange across the alveolar capillary membrane. The etiology of this clinical syndrome is generally either infectious or non-infectious. Early detection of the underlying pathophysiology of the disease and timely initiation of antibiotic therapy is crucial for treatment of infectious causes of acute lung injury. Inflammatory biomarkers have recently gained popularity in critical care medicine to differentiate these two clinically similar entities. We have reviewed a variety of biomarkers related to acute lung injury and their relative value in early diagnosis and management of these patients.