Central venous catheters facilitate the safe administration of parenteral nutrition and concentrated drug and electrolyte solutions, allow measurement of central venous pressures, and permit establishment of reliable venous access in patients with inadequate peripheral venous access. Unfortunately, insertion of such catheters is not risk free. Historically, numerous associated complications have been described, including arterial puncture, which has occurred in about 5% of central venipuncture attempts (range 2% to 15%) (1–5). In certain patients, classic signs of arterial puncture may be absent, and cannulation may occur. Yet, few studies have been published that document the predisposing factors, radiographie findings, and complications of accidental central arterial cannulation. Three illustrative cases are presented.