The propeptide (VWFpp) to von Willebrand factor antigen (VWF:Ag) ratio in Waldenstrom macroglobulinemia (WM). *The VWFpp/VWF:Ag ratio is significantly higher in 7 patients with WM with suspected acquired von Willebrand syndrome (AVWS), compared with 14 patients without suspected AVWS. The latter patients were stratified according to VWF:Ag values identified by the recursive partitioning analysis. Solid line indicates the median.