Following chemotherapy for metastatic nonseminomatous testicular cancer, 86 patients with normal serum markers AFP and HCG underwent resection of residual tumour masses (63 laparotomy, 11 thoracotomy, 12 both). Prognostic factors for relapse and survival were analysed with Kaplan-Meier curves and Cox regression analysis. Putative prognostic factors included age, the primary histology, prechemotherapy level of the tumour markers AFP and HCG, the extent of disease (lymph nodes, lung and hepatic metastases) before and after chemotherapy, the histology of the resected material and the completeness of the surgical procedure. Eleven patients relapsed during follow-up (median 47 months), accounting for a 5 year relapse free percentage of 87.4%. Adverse prognostic factors were (1) prechemotherapy level of HCG (> or = 10,000 IU l-1; (2) incomplete resection; and (3) the extent of disease, especially of lung metastases (prechemotherapy number < or = 3,4-19, > or = 20; or size after chemotherapy > 1 cm; or presence of any residual lung metastasis after chemotherapy without residual abdominal metastases). The histology found at resection was not associated with the risk of relapse, which might be explained by the effectiveness of postresection chemotherapy, which in the majority of these patients was a salvage regimen rather than two further cycles of the initial cytostatics. A good and a poor risk group were formed, based on HCG level and completeness of resection. The effect of salvage chemotherapy after resection of viable cancer cells needs further investigation.