Subclavian vein cannulation as a central venous route is a simple and rapid beside procedure and most reliable method. The supraclavicular approach to the subclavian vein depended on a fixed entry point and accurate angulation of the needle and is particularly free from infection and phlebitis although catheters have been left in situ for long-term period. Tension pneumothorax is a complication of subclavian vein cannulation. The incidence of pneumothorax in patients with chronic obstructive pulmonary disease(COPD) is higher than in the general population and can result in serious respiratory compromise. Because pneumothorax is a serious complication in COPD, its presence must be anticipated so that close and prompt treatment, including immediate re-expansion of the lung, is offered. Authors presented one case that the patient with COPD developed tension pneumothorax in right side lung resulting from inadvertent lung injury during supraclavicular subclavian vein cannulation under general anesthesia and on trendelenberg position. The patient was treated with immediate thoraeostomy and recovered uneventfully.