Background: This study was performed to diagnose von Willebrand disease (vWD) in children with chronic immune thrombocytopenic purpura (ITP). Methods: Seventeen cases of chronic ITP were included in this study. Screening tests and specific tests were performed. These tests were also performed on their families when the patient was diagnosed vWD. Their past histories and family histories for bleeding tendencies were also reviewed. Results: Five cases were diagnosed with vWD: One had a lowlevel of vWF:RCo and factor VIII with a normal level of vWF:Ag, and others had a low level of vWF:RCo and vWF:Ag with a normal level of factor VIII. Among these, two cases showed abnormal screening test results, with prolongation of the aPTT or BT. The vWF multimer test could be performed in three cases, and two cases had a normal pattern and one had a abnormal pattern. Among the five vWD children, the past histories and family histories of a bleeding tendency could be obtained for four vWD patients and three families showed a bleeding tendency. But all the families were found to be normal on the first screening and the specific tests. Conclusion: von Willebrand disease was combined in 5 cases (29.4%) among the 17 chronic ITP children. More evaluations, such as the vWF multimer test and the ristocetin-induced platelet aggregation (RIPA) test are needed to confirm the subtype. Afollow-up test of the same type should be repeated on family members who have a history of bleeding, but they have normal test results for the diagnosis or exclusion of vWD

Keywords: Chronic immune thrombocytopenic purpura, von Willebrand disease, Children