Primary yolk sac tumor of the diaphragm in children is very rare, and diagnosis of a diaphragmatic tumor poses challenges to clinical physicians. Here, we report a primary diaphragmatic yolk sac tumor in a 9-month-old girl, together with a review of 4 earlier reported cases in the English literature. Carboplatin-containing regimen successfully decreased the tumor size and a total resection of the tumor was made subsequently. The patient was disease-free 8 months after the completion of treatment.