Transfusion-related lung injury (TRALI) is the leading cause of mortality following transfusion of blood products. Despite increasing awareness, the condition often remains unrecognised and therefore underreported. A 28-year-old with moderate preeclampsia had a post-partum haemorrhage following emergency caesarean section. Shortly after receiving three units of packed red cells she went into respiratory failure, which progressed to cardiac arrest. She was successfully resuscitated and made a slow but full recovery. Investigation through the National Blood Service confirmed the diagnosis of TRALI. TRALI is an increasingly common life-threatening complication of blood transfusion and should be included in the differential diagnosis of collapse in an obstetric patient who has recently received a blood product transfusion.