Since recombinant hirudin (r-hirudin) has become available, several studies have been published on hirudin for prophylaxis and treatment of thromboembolic complications. Vr-hirudin was shown to be superior even to low-molecular-weight heparin (LMWH) for prophylaxis of deep venous thrombosis (DVT), especially in high-risk patients. Consequently, r-hirudin was expected to be more effective than heparins are in the treatment of thromboembolic events. Vr-hirudin was proved to be safe and efficacious in the therapy of thromboembolic events. However, no benefit could be shown in comparison with heparin. In contrast, in patients suffering from HIT type II, r-hirudin is the drug of choice for the therapy of thromboembolic complications.