Two patients with a long history of unexplained thrombocytopenia, eventually diagnosed with von Willebrand's disease (vWD) type 2B are reported. In one patient with platelet counts of 80 x 10(9)/l 1-desamino-8-D-arginine vasopressin (DDAVP) had a favourable effect during bleeding episodes. The second patient received intermediate purity von Willebrand's factor (vWF)/factor VIII concentrate (Haemate HS), which helped haemostasis during tooth extraction. It increased platelet counts from 15 to 30 x 10(9)/l, whereas platelet transfusions produced no increase, nor prevented severe bleeding during abdominal surgery. Thus the treatment of vWD type 2B might depend on the degree of thrombocytopenia. It is recommended that in patients with mild to moderately decreased platelet counts, DDAVP treatment can be tried, whereas in patients with severely decreased platelet counts intermediate purity vWF/factor VIII concentrate substitution is preferred. In addition, vWD type 2B should be considered in the differential diagnosis of any child with chronic thrombocytopenia as the treatment strategy is different.