The purpose of this phase II study was to determine the effectiveness of hormonal therapy with combined high dose androgen and provera or tamoxifen in patients with advanced renal cell carcinoma. 30 patients with metastatic renal cell carcinoma received testosterone propionate 100 mg intramuscularly (i.m.) 5 times weekly plus provera 400 mg (i.m.) twice weekly until disease progression developed. 20 patients, most of whom had previously failed to respond to androgen and provera, received tamoxifen 100 mg/m2 daily. Of the 30 patients treated with androgen and provera, 3 (10%) developed partial responses of brief duration. 2 of 20 patients (10%) experienced tumour response with tamoxifen, one instance of complete disappearance of pulmonary metastases in a patient whose primary tumour was questionably persistent at post mortem and another case demonstrating disease stability. Combined hormonal therapy offers very little therapeutic advantage in advanced renal cell carcinoma. Tamoxifen, in high dose, exerts anti-tumour effects in a small cohort of cases.