We have performed systematic subsegmentectomy in patients with hepatocellular carcinoma complicated mainly by cirrhosis. Such small anatomical resections have become possible due to the introduction of intraoperative ultrasonography and of vascular occlusion techniques. As a result of our clinical experience involving 163 cases, it has been clarified that subsegmentectomy is a safe procedure (operative mortality rate, 0.6%) and results in a favorable long-term outcome (5-year survival rate, 51%). In the resected specimens, microscopic cancer spread was recognized frequently (portal venous invasion, 41%; intrahepatic metastasis, 31%). Subsegmentectomy is therefore the first procedure of choice in patients who have small hepatocellular carcinoma and chronic hepatitis or cirrhosis.