Malignancy-related thromboembolism, so-called Trousseau's syndrome, can present as acute cerebral infarction, non-bacterial thrombotic endocarditis (NBTE) and migratory thrombophlebitis. It is usually attributed to a cancer-related hypercoagulable state, chronic disseminated intravascular coagulopathy (DIC), or tumour embolism. We report on two patients with adenocarcinoma of the colon and cholangiocarcinoma who developed widespread thromboembolism during disease progression. Both did poorly despite aggressive institution of anticoagulation therapy. These cases emphasize that cerebral infarction or refractory thromboembolism in cancer-treated patients should prompt investigation for recurrent or metastatic disease or progression of the underlying malignancy. Optimal treatment remains to be established.