Thirty-three patients with malignant testicular teratomas and para-aortic metastases exceeding 2 cm in diameter have been treated with radiotherapy, chemotherapy (vinblastine and bleomycin, with or without cis-platinum) or both, followed by surgical excision of the residual para-aortic mass. Removal of a poorly functioning ipsilateral kidney was necessary in 7 cases (21%) and a segment of vena cava was resected in 2 (12.5%) of 16 patients with primary right-sided tumours. Removal was incomplete in only one patient, who had femoral nerve root involvement, and he subsequently died of secondary haemorrhage (operative mortality 3%). Undifferentiated tumour was found in 8 (61%) of 13 patients (Group 1) after radiotherapy, compared with only 2 (15%) of 13 (Group 2) after chemotherapy and radiotherapy, and 4 (57%) of 7 (Group 3) who had chemotherapy only prior to surgery; however, 3 of the Group 3 patients were referred because of evidence of activity in the para-aortic region.