We evaluated the frequency, etiologic factors, outcome, and the comorbid conditions affecting the morbidity and mortality of pulmonary complications in acute childhood leukemia. Sixty-six (40.4%) out of 163 patients developed 79 pulmonary complications. Infectious etiology was the leading cause (92.4%). The most identified infectious agents were Gram (-) bacteria, followed by fungi. Acute respiratory distress syndrome, leukostasis, lymphomatoid granulomatosis, pulmonary edema, and pneumothorax were among the noninfectious causes. The pulmonary complications in the induction and consolidation phase of leukemia therapy were more severe and the mortality rate was higher. Tachypnea, shock, oxygen and mechanical ventilation requirement, disseminated intravascular coagulation, involvement of other organs or systems, cytopenias, requirement of modification in antimicrobial drugs were found to be related with increased mortality risk. The mortality rate of pulmonary complications was 8.9%. Pulmonary infections in the maintenance phase of the therapy were frequently treated with oral antibiotics, and they were generally rapidly taken under control. In conclusion, pulmonary complications are frequent in children with acute leukemia, and early diagnosis and appropriate management are important to avoid mortality owing to pulmonary complications, especially in neutropenic patients receiving induction or consolidation phase of chemotherapy.