Pulmonary blastoma (PB) is an extremely uncommon intrathoracic neoplasm in children. It accounts for 0.5% of all primary malignant tumors of the lung, and 20%-25% of the cases present in childhood. A new case of PB in a 3-year-old girl is discussed with special emphasis on diagnosis and treatment. The authors point out that the possibility of a primary lung tumor should be considered for any childhood cases with intractable signs and symptoms of a space-occupying lesion. A primary lung malignancy should not be excluded only on the basis of the patient's age, and childhood lung disorders should receive the same detailed and vigorous diagnostic evaluation and appropriate treatment given to adults.