METHODS We describe a case of left internal jugular central venous access with rare malpositioning into the internal mammary vein. Despite various confirmatory measures at the time of placement including ultrasonography of the internal jugular vein, as well as blood gas analysis consistent with venous blood by oxygen saturation and good venous flow in all three ports of the catheter, subsequent imaging confirmed misplacement into the internal mammary vein. CONCLUSIONS Central venous access is a frequently used procedure by emergency physicians for a variety of indications. Emergency physicians must be facile with both the technical process of central venous catheter placement, as well as possible pitfalls and complications of the procedure. Common complications, such as bleeding, pneumothorax, arterial injury, infection, and hematomas, are usually well known; less frequently encountered is malposition of the catheter despite seemingly appropriate placement.