Review of the results of treatment of 275 patients with testicular teratomas indicates that the size of para-aortic node metastases as defined by lymphography is closely related to prognosis, and that accurate definition of these metastases is essential in planning treatment. Although para-aortic lymphadenectomy does not appear to be necessary therapeutically or as a staging procedure, excision of residual bulk disease may be required after chemotherapy and radiotherapy. In these cases the residual para-aortic tumour mass should be accurately localised by ultrasonography so the best surgical approach can be used.