The association between cancer and thromboembolic disease is well documented. The procoagulant capacity of tumor cells seems to be related to malignant transformation. In this context, a preventive effect on tumoral progression by the adjunction of an anticoagulant such as vitamin K antagonists, unfractionated heparin or low molecular weight heparin (LMWH) was studied. Some studies concluded to a modest increase in survival in patients treated by LMWH in adjunction to conventional chemotherapy and/or radiotherapy. This benefit seems to be related to an inhibitory effect on tumoral progression. LMWH seems promising in an eventual routine clinical use. However, their type, dose and duration and in which cancers has to be further defined.