Summary Summary: Massive transfusion is most commonly defined as the replacement of the patient‘s total blood volume by stored homologous whole blood or red cell concentrates within 24 hours. In approximately 20- 30% of patients, usually after transfusion of 20 units, a complex bleeding disorder can be observed. The clinical characteristics of microvascular bleeding (MVB) are (a) bleeding from mucous membranes, (b) bleeding from catheter or venepuncture sites, (c) oozing from raw surfaces, (d) generalised petechiae and (e) increasing size of ecchymoses. The best predictive value for the development of MVB have a platelet count of less than 50,000/ µL, fibrinogen levels less than 50 mg/dl, or coagulation factors less than 20 - 30% of normal. Elevated prothrombin times (PT) or partial thromboplastin times (PTT), greater 1.5 times normal, are also predictive for bleeding. Platelet concentrates and fresh frozen plasma are the treatment of first choice, when clotting factor concentrates have to be administered, antithrombin levels should be normalized.