Liver resection is for many patients with primary or secondary hepatic malignancies the only curative treatment option. Often, the complete clearance of the hepatic tumor disease can be only achieved by extended liver resections. Clinical studies have demonstrated that intra-operative blood loss is associated reduced outcome after major liver resection. An effective strategy to reduce blood loss is the occlusion of the portal triad (Pringle manoeuvre). On the other hand, inflow occlusion results in ischemia- and reperfusion (I/R) injury. Randomized trials have shown that ischemic preconditioning (10 min clamping, 10 min reperfusion) and intermittent clamping (15 min clamping, 5 min reperfusion) result in reduction of the I/R injury. Another potential strategy to reduce I/R injury is the pharmacological protection. One promising drug is pentoxyfilline (PTF) which has vasodilative and hemorheologic effects. Furthermore, PTF suppresses the TNF release. These effects may be also protective in major liver resection under inflow occlusion (Pringle manoeuvre)and increase the liver regeneration. Therefore, we designed a randomised prospective trial to investigate the effects of PTF treatment in liver resection under inflow occlusion. The specific aims of the research project are:The investigators hypothecate that pentoxyfilline increases significantly the liver regeneration and reduces significantly ischemia and reperfusion (I/R) injury in liver using aspartate aminotransferase (AST) and alanine aminotransferase (ALT) as marker of I/R injury.