A patient who developed a rhabdomyosarcoma following apparently successful chemotherapy for metastatic germ cell testicular carcinoma is presented. This newly recognized association may be seen particularly in patients whose initial germ cell malignancy contains immature teratoma. Possible reasons for this are discussed. The findings in this patient suggest that re-biopsy of recurrent disease be undertaken wherever possible, particularly where immature teratoma was a feature of the initial histopathology. A proportion of relapsing patients as described may not in fact have recurrent germ cell malignancy, but may have developed high grade, and often chemoresistant sarcomas. These second tumours appear to have an extremely poor prognosis, unless amenable to complete surgical resection.