Analysis of von Willebrand factor (VWF) structure is achieved by performing a highly specialized procedure, VWF multimer analysis. The test is reserved for the reference or specialized laboratory environment. The assay is qualitative (though under some circumstances multimers may be quantified) in that it assesses the overall size distribution of VWF multimers as well as their individual internal structure. The test is used predominantly to type or subtype von Willebrand disease. The analysis of VWF multimers generally consists of four steps: (1) electrophoresis of plasma in an agarose gel, (2) either gel fixation or transfer of the electrophoretic protein product to a membrane, (3) immunodetection of the protein, and (4) evaluation of the protein in the gel or membrane. The assay is complex, time consuming, requires specialized equipment and technical expertise, and is not standardized. Am. J. Hematol., 2010. © 2010 Wiley-Liss, Inc.