A 23-year-old female was admitted to our hospital in July 1987, because of cutaneous macular telangiectasia on her extremities and hypermenorrhea. In 1983, she began to notice small red spots on her palms. During next several years, these telangiectasia increased in number and spread all over her body. In 1986, she had a history of melena and prolonged bleeding after dental extraction. Her lower legs have turned red purple during the gait for a long time. Her older brother and two paternal cousins have experienced frequent epistaxis. The hemostatic laboratory data revealed prolonged IVY bleeding time and APTT, impaired capillary fragility, decreased vWf:Ag and VIII:C levels, depressed Rcof and severe decreased platelet adhesiveness, vWf mobility on two-dimensional crossed immunoelectrophoresis was normal. Platelet aggregation was reduced after addition of ristocetin and collagen. This case was diagnosed Osler-Weber-Rendu disease (Osler disease) associated with von Willebrand's disease (vW disease) type I. Previously, 28 Cases (8 families) with these two disease association have been reported. These disease seems to coexist as an inevitable consequence, because the disorder of vascular endothelial cells where von Willebrand factors are synthesized is a common pathogenetic factor in Osler disease. It is considered that such a case is secondary vW disease. Moreover, previous reports of Osler disease associated with various hemostatic defects are reviewed.