The use of RF energy to treat unresectable liver tumors is unlikely to be curative for most patients; however, a subset of patients treated with RFA may achieve long-term disease-free survival. Longer follow-up of hepatic tumor patients treated with RFA is needed to determine long-term disease-free and overall survival rates. New metastatic tumors develop in many of these patients at an incidence rate comparable with those treated with surgical resection or cryoablation. Surgical resection remains the gold standard for treating metastatic and primary liver tumors; however, few patients are candidates for hepatic resection because of tumor size, number, location, or the presence of cirrhosis too severe to permit liver resection. Cryoablation of unresectable tumors has been an option for several years, but complications associated with the freezing of tissue can be problematic. RFA of unresectable liver tumors provides a relatively safe, highly effective method to achieve local disease control in some liver cancer patients who are not candidates for liver resection. Ongoing research and refinements in RF techniques and equipment may permit effective treatment of larger liver tumors and of malignant tumors at other body sites. Combining RFA of liver tumors with regional and/or systemic adjuvant treatments is being studied in attempts to reduce the incidence of development of new metastases and, thus, improve the overall survival rates of these patients.