The development of image-guided percutaneous techniques for local tumor ablation has been one of the major advances in the treatment of liver malignancies. Over the past two decades, several methods for chemical or thermal tumor destruction have been clinically tested. Among these methods, radiofrequency (RF) ablation is currently established as the primary ablative modality at most institutions. RF ablation is accepted as the best therapeutic choice for patients with early stage hepatocellular carcinoma (HCC) when liver transplantation or surgical resection is not suitable options. In addition, RF ablation is emerging as a viable alternative to surgery for inoperable patients with limited hepatic metastatic disease, especially from colorectal cancer. Several series have shown that RF ablation can result in complete tumor eradication in properly selected candidates, and have provided indirect evidence that the treatment improves survival. In this article, we review technique, indications, and clinical results of percutaneous RF ablation in the treatment of HCC and colorectal hepatic metastases.