Background: Subacute noncardiogenic pulmonary edema is known to be a side effect of high- or intermediate-dose cytosine arabinoside (Ara-C) therapy. This often fatal complication seems to be underestimated, since only few publications concerning this subject are available and clinical and radiographic findings are nonspecific. Patients and Methods 15 g/m2/course) or intermediate-dose (6-15 g/m2/course) Ara-C. Therapy was administered in combination with mitoxantrone (108/115), etoposide (4/115) or daunorubicin (3/115) for treatment of acute myelogenous leukemia (62), acute lymphoblastic leukemia (19), blast crises of chronic myelogenous leukemia (3), or high-grade non-Hodgkin’s lymphoma (5). Results: Pulmonary toxicity attributable to Ara-C therapy was observed in 7 of 115 courses (6%) and appeared 2-18 (median: 10) days after the start of treatment. Three of the affected patients died as a result of respiratory failure and 4 recovered completely. In contrast to the patients who had a lethal course, all patients who recovered had received intravenous corticosteroids at an early stage. Additionally, patients presenting with drug-induced pulmonary toxicity showed considerably more cutaneous reactions related to Ara-C administration (3/7 patients) than the patients without pulmonary toxicity (7/82 patients). Other predisposing factors for the development of pulmonary toxicity were not evaluable. Conclusion: Patients with a history of cutaneous reactions related to Ara-C therapy should be monitored carefully for drug-induced pulmonary toxicity after high-or intermediate-dose Ara-C treatment. If drug-induced pulmonary toxicity is suspected, and other possible underlying causes of the pulmonary changes are excluded, corticosteroid treatment should be started immediatel