Acute lung injury is a kind of common complication after cardiopulmonary bypass. Acute lung injury is attributed to the ischemia-reperfusion injury and systemic inflammatory response syndrome. Several factors common in cardiac surgery with cardiopulmonary bypass may worsen the risk for acute lung injury including atelectasis, transfusion requirement, older age, heart failure, emergency surgery and prolonged duration of bypass. Targets for prevention of acute lung injury include mechanical, surgical and anesthetic interventions that aim to reduce the contact activation, systemic inflammatory response, leukocyte sequestration and hemodilution associated with cardiopulmonary bypass. We aim to review the etiology, risk factors and lung protective strategies for acute lung injury after cardiopulmonary bypass.