The present invention relates to a method for preparing a surgical anti-adhesion barrier film comprising the following steps: a°) a first solution, comprising an oxidized collagen is prepared, b) a polyphosphate compound is added to the solution of a) in a quantity so as to obtain a concentration of polyphosphate ranging from 0.007 to 0.7%, by weight, with respect to the total weight of the solution, c) the pH of the solution obtained in b) is adjusted to about 9 by addition of a base or to about 5.1 by addition of an acid, d) a diluted solution is prepared by adding water to solution of c), e) a first layer of solution obtained in c) is casted on an inert support, f) before complete gelation of the layer obtained in d), a second layer, of diluted solution obtained in d) is applied on top of said first layer and let to gelify, g) the gelified first and second layers are dried to obtain a film. The invention further relates to a film obtainable by such a method and to a surgical implant comprising a prosthetic fabric and such a film.
