Low molecular weight heparins (LMWHs) have extensively replaced unfractionated heparin (UFH) in both thromboprophylaxis and initial treatment of venous thromboembolism (VTE) and their use for such indications is now well established. This paper reviews the role of LMWHs in the long-term treatment of VTE. Venous thrombosis, although a very frequent occurrence in everyday practice, still remains controversial in its treatment. Available literature comparing different LMWHs with UFH and oral anticoagulants (OAs) is presented. Comparison and evaluation of the effectiveness, safety and costs of alternative treatments are also made. The differences of various LMWHs are discussed and the need for separate clinical trials for every single LMWH is highlighted.