Post-chemotherapy tumor residuals in patients with advanced nonseminomatous testicular cancer. Is it necessary to resect all residual masses? A total of 15 patients with advanced nonseminomatous testicular cancer underwent 2 sequential operations (4 in 1 patient) to remove residual masses after cisplatin-based combination chemotherapy. All patients had normal human chorionic gonadotropin and alpha-fetoprotein levels but persistent radiographic masses after chemotherapy. The operations included retroperitoneal lymph node dissection in 13 patients, thoracotomy in 15, hepatic resection in 3 and craniotomy in 1. Histological comparison of the specimens resected during post-chemotherapy operations 1 and 2 demonstrated different patterns in 7 of 15 patients. Of these 7 patients 4 had less favorable pathological features in the specimen removed during the second procedure. Residual malignant tumor or mature teratoma was found in at least 1 site in 12 of the 15 patients and only 3 had complete necrosis or fibrosis in both specimens examined. These data indicate the favorable impact of excising all post-chemotherapy tumor residuals in patients with advanced nonseminomatous testicular cancer. However, in patients with no teratomatous elements in the testicular tumor and complete necrosis or fibrosis in the initial post-chemotherapy operation specimen the probability of complete necrosis or fibrosis in remaining tumors appears to be high. 