The evaluation of radioimmunotherapy using 131I-anti HCC isoferritin IgG antibody in the multimodality treatment of HCC was reported. Forty three patients with surgically verified unresectable HCC have been treated by radioimmunotherapy as a part of multimodality treatment during 1985-1990. The short-term responses and prolong survival were compared with that in control group of 39 patients with HCC receiving conventional multimodality treatment. The rates of tumor shrinkage, AFP level decline and second resection in radioimmunotherapy group were 67.4% (29/43), 69.6% (16/23) and 30.2% (13/43) respectively, significantly higher than those in control group 23.1% (15/39), 40.0% (8/20) and 10.3% (4/39) respectively. The 1, 3, 5-year survival rates were 61.5%, 40.4% and 35.5% in radioimmunotherapy group, however, in control group were 51.3%, 20.1% and 15.5%, respectively. The results suggested that radioimmunotherapy is one of modalities of choice, particularly for the treatment of unresectable HCC in the multimodality treatment regimen.