A 34-year old woman who developed persistent and severe acute respiratory distress syndrome with underlying myelomonocytic leukemia (M4FAB) is described. After ruling out the most common causes of pulmonary infiltration in this type of patient and one week of broad spectrum antibiotics and steroids therapy, we proposed leukemic pulmonary infiltration as etiological diagnosis. Despite using a protective ventilatory strategy, recruitment maneuvers, prone position and high frequency oscillatory ventilation, her gas exchange became worse. Under this condition we used a Pumpless-Extracorporeal life assist (PELA) and begun chemotherapy. The method, arterial blood gases, hemodynamic parameters and ventilatory mechanics before and after its use are described. The patient remained on P-ELA for nine days; one week later she was extubated and ten days after she was discharged from the Intensive Care Unit the patient left the hospital in good health condition.