Two patients, a man aged 69 and a woman aged 64, were diagnosed with Von-Willebrand syndrome caused by monoclonal gammopathy. The man, who was admitted for hip surgery, had a history of long episodes of epistaxis. The patient was treated with immunoglobulin and the hip operation was carried out with no complications. The woman suffered from haemorrhagic diathesis. She was advised that should she undergo an invasive procedure then treatment with a prophylactic with intravenous immunoglobulin or Von-Willebrand factor (VWF)/factor-VIII-concentrates must be administered. Acquired Von-Willebrand syndrome is a rare condition with an estimated prevalence of 0.04-0.13%. It is linked to a large number of underlying diseases such as paraproteinaemia, multiple myeloma (Kahler's disease), myeloproliferative disease, lymphoproliferative disease, auto-immune disease, solid tumours and hypothyroidism. Recognition depends on a careful case-history and identification of the underlying disease. For its diagnosis VWF antigen. VWF propeptide, activated partial thromboplastin time and factor VIII are of importance. Technically, it is difficult to show the presence of VWF antibodies as it concerns a heterogeneous group of antibodies. There are two pillars of treatment: symptomatic treatment of the bleeding tendencies using desmopressin, VWF-concentrate or intravenous gammaglobulin, and treatment of the underlying disease. The latter form of treatment can lead to acquired Von-Willebrand-syndrome disappearing altogether.