A case of iatrogenic subclavian arteriovenous fistula is reported. An intracath had been inserted percutaneously into the left subclavian vein to monitor the central venous pressure during aortic valve surgery. On the second postoperative day a thrill and continuous murmur were detected at the left subclavian region. Left subclavian arteriogram and catheterization studies confirmed the diagnosis of subclavian arteriovenous fistula. The lesion was treated surgically with satisfactory results.