We present a patient with Lady Windermere syndrome after coronary bypass operation. To avoid the sternal pain that occurred after every cough episode, this patient used to receive large doses of antitussive drugs. In a poorly drained lung, this usage leads to the development of regions of colonization with Mycobacterium avium complex. It is concerning that the lack of diagnosis for 18 months in this patient occurred because of the insidious symptoms that mimic bronchitis. This case emphasizes how important it is for patients after a median sternotomy to receive adequate analgesic and physiotherapeutic support in order to avoid chronic inflammation and infection of the lungs.