A few years ago surgical resection was the only treatment modality for primary and metastatic liver tumors. However, most of the liver tumors are diagnosed at advanced stage and are unresectable. Criteria for unresectability are: uncontrolled extrahepatic disease, extensive intrahepatic tumor growth, insufficient remnant liver volume and severe co-morbid disease. Several therapeutic strategies have been developed to deal with primarily unresectable tumors. A downstaging ("downsizing") of hepatocellular carcinoma (HCC) can be reached by transarterial chemoembolisation (TACE) or local tumor ablation using ethanol injection, cryosurgery and radiofrequency. Preoperative unilateral portal vein embolization resulting in hypertrophy of the remnant liver volume permits to resect some patients with former unresectable liver tumors. Furthermore, liver transplantation is an option for patients with early stage HCC and liver cirrhosis. Preoperative downstaging of colorectal metastases can be achieved with neoadjuvant chemotherapy, whereas TACE, ethanol injection and liver transplantation are no established options for these patients. So far, there are no standardized guidelines for the treatment of patients with unresectable primary or metastatic liver tumors. In this review we aim to describe the different approaches suggested in the literature and to present our algorithms for the management of patients with liver tumors.