Blood transfusion saves many lives but carries the risk of injury, such as severe damage to the lungs. In 'Bedside to Bench', Janet S. Lee and Mark T. Gladwin examine the implications of clinical studies assessing such damage. The risk of injury seems to increase with the number of units transfused and may be greater with blood that has been stored longer. Researchers have yet to understand why, but several mechanisms are under scrutiny. In 'Bench to Bedside', Paul S. Frenette and Narla Mohandas discuss recent studies pinpointing a trigger—a specific antigen on neutrophils for a severe form of transfusion-related acute lung injury (TRALI). The findings could lead to new ways to diagnose TRALI and identify people at risk.