The cases of two children under three years of age with primary pulmonary rhabdomyosarcoma and no associated lung malformations are reported and a review of the literature is presented. In both, complete surgical removal of the tumor was performed and histologic examination revealed embryonal subtype. Flow cytometric assessment showed a tumor-cell diploid DNA content. Postoperative radio- and chemotherapy were carried out, but in spite of treatment both girls died because of disease progression, fourteen and nine months after diagnosis. The importance of associated cystic lung malformations and DNA content in predicting clinical outcome of primary pulmonary rhabdomyosarcoma is evaluated.