We report a Sertoli-Leydig cell (SLC) tumor of the right ovary in a 10-year-old girl, which was dealt with surgical removal. Three months after resection, she presented with a new episode of acute abdomen because of an abdominal mass, which histologically was compatible with an undifferentiated embryonal rhabdomyosarcoma. Chemotherapy, according to SIOP-??? 89 protocol, was administered additionally to radiotherapy (3,960 cGy). Three years after completing treatment, the patient developed a painful swelling at her left upper arm. The diagnosis was Ewing sarcoma of the humerus, which was confirmed by identification of the typical 11; 22 translocation on cytogenetic and molecular analysis of the tumor tissue. The patient died 14 months from Ewing diagnosis due to progressive disease.