Radiofrequency (RF) tumor ablation has been demonstrated as a reliable method for creating thermally induced coagulation necrosis using either a percutaneous approach with image-guidance or direct surgical placement of thin electrodes into tissues to be treated. Early clinical trials with this technology have studied the treatment of hepatic, cerebral, and bony malignancies. However, more recently this technology has been used to treat a host of malignant processes throughout the body. This article will discuss the principles and technical considerations of RF ablation with the goal of defining optimal parameters for the therapy of focal lesions. This includes technologic innovations that permit large volume tumor ablation (i.e., hooked and internally cooled electrodes), as well as methods and adjuvant therapies that can modulate tumor biophysiology to permit improved tumor destruction (i.e, altered tissue conductivity and blood flow). Potential biophysical limitations to RF induced coagulation, such as perfusion mediated tissue cooling (vascular flow) will likewise be discussed. Lastly, the principles governing safe usage of the system, such as proper grounding pad placement, will be adressed.