Pulmonary blastoma is a rare primary neoplasm of the lung. Approximately 25% of the reported cases have occurred in pediatric patients. The authors found 45 cases of these tumors in children aged < or = 16 years, and report two more cases of pulmonary blastoma--in a 3 1/2-year-old boy and a 22-month-old girl. Because these tumors are considered malignant, surgical excision is recommended.