Percutaneous radiofrequency (RF) ablation represents a technique for hyperthermal tumor ablation. Understanding the underlying mechanism and technical basics of RF ablation is essential to ensure safe and effective coagulation of the tumor tissue. The technical development of RF devices enables reproducible energy application and coagulation of tumor tissue. Several RF devices and protocols for energy application are available; however, clinical experience has shown that the standard protocols provided by the different manufacturers may have to be adapted to the individual situation because of the variable underlying tissue and tumor biology. Therefore, the interventional radiologist has to be familiar with the relationship between the parameters of RF ablation and the RF devices applied. Beside the technical aspects of RF ablation, the determination of appropriate indications for ablation therapy represents a key aspect for a reasonable and an effective clinical application of RF ablation. Considerations regarding the indication of RF ablation in relation to different tumor types and organ sites are discussed in subsequent sections.