Of 21 patients who underwent bench surgery for renal malignancies (renal cell carcinoma in 16 and transitional cell carcinoma in 5) 15 also had autotransplantation and 6 did not. In 5 patients the contralateral kidney was removed simultaneously for synchronous bilateral renal malignancy, and 16 had cancer in a solitary kidney. In the 3 patients who underwent nephrectomy for complications after autotransplantation no evidence of residual tumor was noted on histopathological examination. Of 9 patients 1 (11 per cent) had local recurrence after successful autotransplantation (renal cell carcinoma). Two patients with transitional cell carcinoma died of metastatic disease. Treatment failed in 31 per cent of the 16 patients with renal cell carcinoma (metastatic disease in 4 and metastatic disease with local recurrence in 1). Removal of solitary or synchronous bilateral renal cell cancer by bench surgery with subsequent autotransplantation is effective. For high grade transitional cell carcinoma of a solitary kidney its value is doubtful without adjuvant systemic treatment.