A new method for mapping hepatic subsegment: counterstaining identification technique. Hepatic subsegmentectomy requires identification of the borders of tumor-bearing subsegment, usually achieved by injecting dye into the portal veins feeding the domain. We describe an alternative technique for performing systematic subsegmentectomy in patients with cirrhosis and hepatocellular carcinoma, in whom hepatic arterial and portal venous embolizations were already performed as a preoperative adjuvant. Under ultrasonic guidance, each of the neighboring portal units is sequentially stained, thus defining the avascular subsegment to be resected as the nonstaining area. This allows the subsegment to be totally resected. This counterstaining identification technique can be used for all subsegments undergoing complete embolization and for other situations in which the usual staining method is impossible because of the presence of arterioportal shunting or portal tumor thrombus. 