Anatomic liver resection can be performed without vascular occlusion, but controlling blood loss during liver parenchyma dissection by compression or clamping of vessels in the liver hilus is almost the rule. The aim of this study is to assess the negative consequences of different types of occlusion techniques used during liver parenchyma dissection. From 2001 to 2003, 43 anatomical liver resections were performed in patients with primary and metastatic tumors. Patients were divided into three groups according to the duration and the type of occlusion of incoming blood vessels in the hepatoduodenal ligament (continuous over 20 min, continuous under 20 min, or interrupted blood-vessel occlusion for 5 min after every 20 min of occlusion). Blood level of bilirubin, ALT, AST and prothrombin time were evaluated in the postoperative period. Within the continuous occlusion group that lasted longer than 20 minutes (37 +/- 14 min) increase in levels of bilirubin and liver enzymes and decrease of prothrombin time were noted as compared to the group with occlusion shorter than 20 minutes and to the group with intermittent occlusion over 20 minutes (34 +/- 5 min). From results issued, it can be seen that using intermittent occlusion during liver parenchyma dissection lasting longer than 20 minutes causes less ischemic-reperfusion injury in the remaining liver parenchyma than by using continual occlusion.