In this treatise, we will address one of the higher-risk procedures, subclavian vein cannulation, that a practitioner may undertake in the care of complex patients. All cardiothoracic surgeons and their trainees will need, on occasion, to put in central lines in a variety of circumstances, including in the operating room, in the intensive care unit, in emergency circumstances, and, occasionally, when other practitioners have been unsuccessful in their attempts to place a central line. We will describe, in detail, the anatomy of the subclavian vein, the preparation of the patient for subclavian vein cannulation, the infraclavicular approach to cannulation of the vein, and a few notes about the supraclavicular approach to the subclavian vein. It is self-evident that the priorities of central venous cannulation include safety of insertion, minimizing clot formation, and avoiding infection. We will dwell primarily on the principles of safe subclavian line insertion.