Summary. Background: Because the number of elderly von Willebrand disease (VWD) patients is increasing, the pathophysiology of aging in VWD has become increasingly relevant. Objectives: To assess age-related changes in von Willebrand factor (VWF) and factor VIII (FVIII) levels and to compare age-related differences in bleeding phenotype between elderly VWD patients and those < 65 years. We also studied co-morbidity in elderly patients. Patients/ Methods: We included VWD patients with VWF levels ≤ 30 U dL À1 in the nationwide cross-sectional 'Willebrand in the Netherlands' (WiN-) study. Patients reported bleeding episodes and treatment of VWD in the year preceding inclusion and during life. This was compared between VWD patients older (n = 71) and younger (16-64 years, n = 593) than 65 years. In elderly patients, agerelated changes in VWF and FVIII levels were studied longitudinally by including all historically measured levels. All medical records were examined for co-morbidity. Results: In elderly type 1 patients, a decade age increase was associated with a 3.5 U dL À1 (95% CI, À0.6 to 7.6) VWF:Ag increase and 7.1 U dL À1 (95% CI, 0.7 to 13.4) FVIII:C increase. This increase was not observed in elderly type 2 patients. Elderly type 2 patients reported significantly more bleeding symptoms in the year preceding inclusion than younger patients (16/27, 59% vs. 87/ 221, 39%; P = 0.048), which was not observed in type 1 VWD. Conclusions: von Willebrand factor parameters and bleeding phenotype evolve with increasing age in VWD. VWF and FVIII levels increase with age in type 1 patients with no mitigation in bleeding phenotype. In type 2 patients VWF parameters do not increase with age and in these patients aging is accompanied by increased bleeding.