Abstract: A method for the qualitative and quantitative determination of multimers of fibrinogen and of von Willebrand factor by gel electrophoresis, in which a sample containing von Willebrand factor (vWF) or fibrinogen is fractionated by submarine electrophoresis using a continuous, homogeneous agarose gel free of lumps, and the multimer bands are visualized immunochemically after a western blot analysis by a specific antibody-enzyme conjugate on the blotting membrane or by a suitable dye, preferably with a blue stain, in the gel, is described.