Abstract
Factor VIII activity and factor VIII related--or Willebrand--antigen were studied in 49 known carriers of haemophilia A and 31 normal women, and the data were analysed by four statistical approaches. Sixteen per cent of normals and 18% of carriers were misclassified, overlapping with the other group. Although the percentage of carriers detected is higher when taking into account the results of both biological and immunological factor VIII, it is lower than others recently reported, and the discrepancies between the results obtained are discussed.