Image-guided procedures continue to offer minimally invasive alternatives to traditional surgery. Accurate placement of needles, probes, catheters, and biopsy guns is of paramount importance to ensure the success of such procedures. Electromagnetic navigation systems promise improved targeting of lesions during cases that include percutaneous biopsy or ablation. Understanding the principles, technique, indications, and pitfalls of this technique will become increasingly important in the clinical practice of interventional radiology, and warrants review.