The development of acute respiratory failure (ARF) in patients with hematologic disorders (HDs) is a life-threatening condition which does not respond well to intensive therapy. We present our experience in the use of intensive therapy for a group of 30 patients suffering from leukemia (21 cases), bone-marrow aplasia (6 cases), or lymphoma (3 cases). Seven had undergone bone-marrow transplantation. All 30 patients were hypoxemic and responded poorly to the administration of high oxygen concentrations via face mask. All were admitted to our intensive respiratory unit (IRU), where 26 received oxygen via mechanical ventilation, and 4 received continuous positive airway pressure (CPAP). Definitive diagnosis was established in 19 (63%) patients. A premortem diagnosis obtained in 8 (26%) cases did not change therapy. The diagnostic accuracy of serology and transbronchial biopsy was low. Of the 6 (20%) patients who recovered from ARF, only 2 were discharged from the hospital. The remaining 24 (80%) patients died in the IRU.