The multimeric analysis was carried out on the plasma of 18 patients with severe von Willebrand's disease (vWD) using two different types of agarose: Seakem HGT(P) and Seaplaque LGT. No pattern was found in any of the patients using Seakem HGT(P). On the contrary, by Seaplaque LGT, a multimeric pattern was found in four patients belonging to three different families, indicating that it is possible to identify and characterize variable multimeric patterns also in type III vWD.