Cancer patients are at high risk of venous thromboembolism (VTE), and the combination of these two conditions is well known as Trousseau's syndrome. Here we present four cases of Trousseau's syndrome associated with advanced lung adenocarcinoma. In addition to fibrinogen degradation products (FDP) and D-dimer, the levels of mucin-producing markers, such as KL-6, were elevated. There is a possibility that mucin production may be associated with cancer-related VTE.