Purpose: Tachypnea in children is associated with respiratory disorders and nonrespiratory disorders such as cardiac disease, metabolic acidosis, fever, pain, and anxiety. Pulmonary embolism is seldom considered by pediatricians as a cause of tachypnea. Patients and Methods: Three children of various ages with persistent tachypnea are described: a girl after orthopedic surgery for kyphoscoliosis, a boy with nephrotic syndrome, and a neonate with Hirschsprung disease. Other causes of tachypnea were diagnosed and treated before pulmonary embolism was considered. Results: Ventilation- perfusion scanning appeared to be highly probable for pulmonary embolism in these patients. Anticoagulant therapy was started. Conclusion: Pulmonary embolism should be kept in mind in children with tachypnea, especially when other risk factors for venous thromboembolism are present, to avoid delay in anticoagulant treatment and a fatal outcome.