By means of genealogical and laboratory-diagnostic examinations in the district of Magdeburg 59 patients with a von-Willebrand-Jürgens-syndrome and 2 patients with thrombasthenia were detected. On the basis of the laboratory data and the severity of the inclination to haemorrhage in patients with von-Willebrand-Jürgens-syndrome a subdivision into type I (severe from), type I (easy form) and type II was made. The diagnosis was rendered difficult by the appearance of clinically asymptomatic carriers of signs. The experiences hitherto made in the dispensary care and the use of the laboratory programme are estimated.