Approved indications for the recombinant hirudins lepirudin (Refludan(R)) und desirudin (Revasc(R)) are therapy of heparin-induced thrombocytopenia (HIT) and thrombosis prophylaxis following knee or hip replacement surgery. Kidney function dependent pharmacokinetics and their capability of inducing antibodies directed against hirudin are characteristic of this class of drugs. However, close dose-monitoring allows safe and effective use of both compounds. While lepirudin is used widely, besides danaparoid, for treatment of HIT, desirudin has not yet been widely accepted for thrombosis prophylaxis following knee or hip replacement surgery.