Effects of reduction surgery combined with chemotherapy on DAB induced hepatoma were investigated. DAB hepatoma was transplanted in the liver and subcutaneous tissue of rats. The results were as follows; 1. Reduction surgery prolonged the survival time of rats with DAB induced hepatoma, either in liver (5, 7 days, p less than 0.001) and subcutaneous tissue(15.9 days, p less than 0.01). 2. Synchronization chemotherapy with MMC and ADM showed inhibitory effect on cell growth in the cultured human hepatoma cells. (p less than 0.01) 3. Reduction surgery with combined chemotherapy prolonged the survival time 3.9 days compared with reduction surgery only. (p less than 0.05) In conclusion, it was suggested that reduction surgery with synchronization chemotherapy is beneficial for improvement of the prognosis in patients with unresectable hepatic tumors.