The rising incidence of abdominal malignancies such as hepatocellular carcinoma (HCC) and renal cell carcinoma presents several challenges. Although surgery typically provides the best chance for cure, many patients are not surgical candidates. Innovative percutaneous therapies such as transarterial chemoembolization (TACE), radioembolization, and radiofrequency ablation (RFA) are increasingly being utilized as alternative treatment modalities, in some cases, with proven survival benefit. With the rise in interventional oncology, radiologists are being increasingly asked to interpret posttreatment imaging examinations that are critical to assessing treatment efficacy and complications. This article reviews the imaging manifestations of the most common percutaneous therapies, with special emphasis on TACE and RFA. Imaging findings of treatment-induced tumor necrosis, viable tumor, complications, and, in particular, benign ancillary findings that may be confused with viable tumor are reviewed, as manifested on computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET).