A dry preparation having a foam-like and, respectively, fleece-like structure obtained by freeze-drying consists, apart from thrombin in at least catalytically active amounts, substantially of approx. 10 to 95% by weight of fibrin and approx. 5 to 90% by weight of fibrinogen. For the preparation thereof, fibrin is produced in situ in an aqueous solution containing fibrinogen and thrombin and the resultant reaction mixture is deep-frozen and lyophilized. As further constituents of the dry preparation active substances such as e.g. antibiotics, natural bone material and/or a synthetic, bone-forming substitute, glycoproteins, coagulation-conducive substances and the like and/or fibrinolysis inhibitors come into consideration. The dry preparation is provided mainly for use as a wound toilet material, as a filling material for bone cavities and/or as a supporting material for further active substances.