The present paper examines the relationship between the patterns of intrahepatic recurrence after resections of hepatocellular carcinoma and surgical margins in cases located in the anterosuperior subsegment of the liver. In 95 curative resections of the liver for hepatocellular carcinomas less than 5 cm in size, 29 tumors were located in the anterosuperior subsegment of the liver. The recurrence rates of tumors in the anterosuperior subsegment and other regions were 16/29 (55.2%) and 39/66 (59.1%), respectively. Recurrences near the resection line were significantly more common in the anterosuperior subsegment (6/29) than in other regions (2/66) of the liver (P < 0.05). The surgical margin from the tumor edge to the resection line was significantly shorter in tumors of the anterosuperior subsegment (4.6 +/- 9.7 mm) than in those of other regions (9.7 +/- 10.6 mm) (P < 0.01). The effect of an argon beam tissue coagulator was also examined in rat livers. Exposure to an argon beam tissue coagulator for 10, 30 and 60 seconds at a power setting of 100 watts was capable of burning out tissue to a depth of 6.0, 10.5 and 13.3 mm from the resection line of the rat liver, respectively. An exposure of 10 seconds is thought to be sufficient to destroy any microscopic residues of malignant cells near the resection line. Thus, an argon tissue coagulator could potentially be of value for the prophylaxis of recurrence near the resected surface.