In the last two years,42 children,aged 1-15 years, admitted to our Department for pathologies with endothelial damage,in presence of bleeding symptoms,were enrolled in this study. Aim of the study was to diagnose von Willebrand disease in children with bleeding manifestations,because screening tests alone may be normal in individuals with vWD. In a total of 42 subjects,the bleeding time and partial thromboplastin time were measured. We found these tests to be prolonged only in two patients (4.8%); they were affected by vWD previously identified. Von Willebrand factor Antigen (vWF:Ag) and ristocetin cofactor activity (Ricof) were evaluated in 40 children,unidentified as patients affected by vWD with haemostasis screening tests. In 15 cases (37.5%) the vWF:Ag was abnormal; in 21 children (52.5%) Ricof resulted abnormal. Four cases (10%) presented these specific measurements in normal range, therefore they underwent the determination of FVIII procoagulant level (FVIII:C), which resulted significantly reducted in all cases (100%). The combination of vWF activity by the ristocetin cofactor method, vWF:Ag, FVIII:C with less sensitive screening tests increased the number of identified patients affected by vWD up to 17 cases (40.4%). From the evaluation of vWF activity and vWF antigen level we detected 8 patients (47%) with type I vWD;7 patients (41.2%) with type IIA vWd;1 patient (5.9%) affected by type IIC vWd and 1 patient (5.9%) with type III vWD. A possible explanation of a so high prevalence of von Willebrand disease in our study would be that the sample population is represented by select children with bleeding symptoms, even if family history for haemorrhagic diathesis was negative, except two cases. Since these pathologies are based on endothelial dysfunction,the vWF values could result higher than the real,because of an increased release of vWF from endothelium itself. It was necessary to treat only the patient affected by type IIC vWD with desmopressin because of a not self-limiting haemorrhage. All the other cases did not require any treatment,since they presented mild bleeding symptoms.