CO2 possesses many advantages over conventional iodinated contrast agents used for arteriography. It is nonallergic and lacks renal toxicity. Its unique properties permit use of smaller catheters in diagnostic and therapeutic angiographic procedures, allow optimal vascular imaging of various neoplasm, assist in detection of occult gastrointestinal bleeding, and facilitate TIPS procedures. With digital subtraction techniques and stacking programs, CO2 arteriography is as accurate as iodinated contrast studies in most patients and thus is the preferred arterial imaging technique in patients with contrast allergy and renal insufficiency. CO2 is also extremely inexpensive compared with available contrast agents. Understanding of the effects of buoyancy and compressibility is necessary for safe, controlled delivery of CO2 during arteriography, but only rare complications have occurred in our large experience with CO2 angiography. Thus, use of CO2 as an arterial contrast agent significantly expands the safety and utility of arterial imaging in patients with peripheral vascular disease.