Human lymphoblastoid interferon (IFN-alpha MOR-22; OIF) was administered to forty-two patients suffering from renal cell carcinoma. Twenty-six patients with metastatic lesions or primary tumor were treated in a clinical trial with either MOR-22 alone or combination of MOR-22 and UFT (or FT-207). The efficacy was assessed in ten of twenty patients who had received MOR-22 alone for more than eight weeks, but objective response was not observed. The efficacy was done in eight of fourteen patients with MOR-22 and UFT (or FT-207) in combination. Complete response was achieved in one, and partial response in two, with an objective response rate of 37.5%. But the difference was no statistically significant in the survival rate of each therapy. In evaluable twenty patients with MOR-22 prophylactically, there was only one case who had occurred lung metastases with a refractory rate of 8.3%. Forty-one patients were examined for side effects to drugs. The main side effects were fever, anorexia, general fatigue, hematologic toxicities, and hepatic dysfunction in both therapy. These side effects occurred with more increased frequency in combination therapy of UFT (or FT-207) compared to MOR-22 alone.