Previously, we reported the effects of human lymphoblastoid interferon (HLBI), using a transplantable human renal cell carcinoma strain (AM-RC-3) in nude mice established in our laboratory. An overall anticancer effect was found from its combination with UFT (Ft-207t uracil). In the present investigation, we examined the clinical effectiveness when HLBI was administered alone or in combination with UFT to the patients. Seventy-three patients who had undergone curative surgery were divided into 3 groups, according to the type of adjuvant therapy. The HLBI group consisted of 38 patients, including those administered the agent alone over 50 times for more than six months, and or those to whom it was given in combination with UFT. The second group of 23 patients had been treated with hormones, radiotherapy, or with an anticancer drug (Fluoride pyrimidine group), while the last group of 17 patients underwent no postoperative adjuvant therapy. The survival rate calculated by the Kaplan-Meier method revealed no significant effects of HLBI on the survival period, but a significant difference (p < 0.05) was found in the HLBI group compared to the other groups in terms of much higher non-recurrence rate. When HLBI was administered alone or in combination with UFT, a definite anticancer effect was seen in 6 (complete response 3, partial response 2, minor response (MR) 1, no change 5, progression of disease 14) of the 25 treated patients. Fourteen of the 25, treated patients had postoperative recurrence, and 11 patients had distant metastases, at the time of diagnosis which were considered to be progressive and measurable lesions. In 6 patients the response was better than MR, with the effective rate being 24%. Four of the 6 patients had received HLBI in combination with UFT, which suggests a clinical effect in this combination. However, the effectiveness was limited to the lung lesions, more effective treatment of the lesions in other sites is required.