In 1979 we reported a phase I trial involving 6 patients treated with immune ribonucleic acid for renal cell carcinoma. Since that report 27 patients with stage III or IV renal cell carcinoma have been assessed in a phase II trial. All patients have undergone excision of the primary tumor or superficial metastases, injection of tumor into guinea pigs and harvesting of immune ribonucleic acid. Autologous lymphocytes, obtained by plasmapheresis on an outpatient basis, have been incubated with immune ribonucleic acid and reinfused into the host. Results indicate complete response in 1 patient for more than 61 months, partial response in 5 patients for 6 to 10 months and stabilization in 10 patients for 2 to 8 months, all of whom had progressive disease before the institution of therapy. Six patients with continued progressive disease died at a median of 2 months after therapy. Of 5 patients treated in an adjuvant fashion only 1 has had a relapse from 9 to 18 months after therapy. Patients with pulmonary metastases seem to represent the most favorable group for this passive form of immunotherapy. This therapy would seem to offer reasonable alternatives in selected patients with advanced disease.