Abstract: The purpose of this refresher course will be to review the role of sonography in guidance of radiofrequency ablation of solid organs. Initially, RF ablation was proposed as a method of treating both primary (hepatocellular carcinoma) and secondary (metastatic disease to the liver). While RF ablation can be guided by either sonography or CT sonographic guidance has several advantages. These advantages include its real-time capabilities, lack of ionizing radiation, ability to visualize large vessels in the path of needle placement and the ability to monitor continuous RF ablation. In addition to radiofrequency ablation techniques within the liver, RF has been performed under sonographic guidance in other organs, including the kidney for treatment of renal cell carcinoma. A similar technique is used in performance of RF ablation in the kidney as it is in the liver. In fact, ultrasound has been proven to be an ideal method of guiding probe placement for radiofrequency ablation in other areas of the body, including radiofrequency ablation of the breast and RF ablation of peripheral lung nodules. In some cases, ultrasound is utilized with CT in guidance of RF ablation in other areas such as bony tumors. This presentation will review the full spectrum of the use of sonography to guide RF ablation in solid organs.