In patients with leukaemia, acute respiratory distress syndrome (ARDS) secondary to intensified chemotherapy-induced immunosuppression is a devastating disorder resulting in high morbidity and mortality. Compared to standard indications for extracorporeal membrane oxygenation (ECMO), cytopenia further increases the risks of infection and bleeding. We describe the use of ECMO in four children with ARDS and leukaemia. Two patients (50%) survived, pulmonary function recovered and they are in prolonged first remission. The two other patients died from ARDS and pulmonary leukaemic infiltration. Although ECMO support is a high-risk setup for nosocomial infection we observed no additional septic episodes. All patients had a highly increased demand for packed platelet and red blood cell transfusions. This increased demand and unmanageable chronic bleeding into both lungs in one patient were probably caused by a combination of coagulopathy from the primary illness, the use of anticoagulants, chemotherapy-induced cytopenia, and a reduced survival rate of platelets and red cells due to permanent contact to foreign surface. We concluded that ECMO is a supportive tool to reduce the incidence of early death, treatment-related mortality and, ultimately, to improve overall survival in childhood leukaemia.