Non-bacterial thrombotic endocarditis is a recognised complication of malignancy (occurring in 0.3-9.3% of patients in autopsy series), and is most commonly associated with lung cancer. We describe a fatal case of non-bacterial thrombotic endocarditis associated with stage IIIB adenocarcinoma of the lung in which the transoesophageal echocardiogram was negative. Recommendations for management of such cases are given.