This article describes an approach to image-guided tumor ablation, a major tool for cancer treatment in interventional oncology. An overview of the discipline of tumor ablation is followed by a review of the diseases affecting the liver; then, more in-depth discussion of percutaneous ethanol injection, radiofrequency ablation, cryoablation, and microwave ablation is offered. Inasmuch as ultrasound is usually the best imaging modality for applicator placement in the liver and kidney, particular attention will be given to the merits and techniques of this guidance method.