In 12 vascular and 17 trauma cases the changes in the coagulation system due to intraoperative autotransfusion (IAT) were examined immediately after the IAT as well as 24, 48, 72 h and one week later. The following parameters were monitored: 1. Platelet count. --2. Prothrombin-time, partial-thromboplastin-time, factors II, V, VII, X and thrombin-clotting-time. --3. Fibrinogen, alpha-1-antitrypsin, alpha-2-macroglobulin, antithrombin III and plasminogen in 5 trauma cases. --4. Euglobulin-Lysis-Time. --After the IAT a loss of platelets, factors I, II, V, X, plasminogen and antithrombin III was found. Alpha-1-antitrypsin and alpha-2-macroglobulin remained unchanged or showed a slight increase. 24 h after treatment with Ugurol and heparin, fresh frozen plasma, fibrinogen and Cohn I-fraction in selected cases, an increasing normalisation of most parameters was seen, except for the plasma proteins active in coagulation. They showed a combination of "consumption coagulophathy" and "hyperfibrinolysis" up to the 7th day. Under treatment outlines above even marked laboratory changes remained without any clinical significance. Thus our results confirm that IAT does not cause any additional irreversible damage to the coagulation system. Therefore IAT can be considered as method of choice for the emergency treatment of massive bleeding.