The von Willebrand syndrome is probably the most frequent heritable bleeding disorder. The pathophysiological key-role plays the impaired platelet adhesion at sites of vascular injury. It is caused by the quantitative or qualitative abnormal von Willebrand factor. Experimental work of previous years led to a better understanding of the structure and function of the factor VIII-von Willebrand factor complex. This knowledge was important for a new classification of the von Willebrand disease.