A new operative procedure for systematic subsegmentectomy guided by ultrasound has been described. This operation consists of operative sonography, ultrasonically guided puncture and injection of dye and hemihepatic blood occlusion. Systematic subsegmentectomy was performed upon 57 patients without operative mortality. The cumulative one year survival rate of 35 patients with hepatocellular carcinoma who underwent operation at our hospital was 80.3 per cent. The two and three year survival rates were 63.3 and 52.6 per cent, respectively.