The aim of this study was to establish whether using a percutaneously inserted metallic coil as a target facilitates the radiofrequency (RF) ablation of tumors poorly seen on unenhanced computed tomography (CT) or ultrasound (US) studies. We inserted a metallic coil percutaneously via a 21-gauge needle under CT guidance into five tumors during the phase of contrast enhancement in five patients. The coil was subsequently used as a target to guide placement of the RF electrode under fluoroscopic guidance. The precision of position was then checked with CT or US. We also carried out a small experimental study to establish the effect of metallic coils on the pattern of coagulation induced by RF. Placement of a metallic coil into the tumor enabled rapid and accurate placement of the RF electrode. The tumors were ablated with no adverse effects. The experimental study showed that the area of coagulation extends predictably along the coil. The application of the above technique is useful when using RF to ablate tumors poorly visualized on US and unenhanced CT.