Although the incidence of haemophilia A is reportedly uniform across ethnic groups, the prevalence varies in different countries. This suggests variability in the effectiveness of diagnostic strategies which is of particular importance in the recognition of milder forms of the disease. To assess the different laboratory tests that are used in the diagnosis and subsequent management of haemophilia A we carried out a web-based survey of established haemophilia centres. This was sent to 13 haemophilia physicians from haemophilia-treatment centres in Germany, Italy, Spain, South Africa, Taiwan, Norway, Canada, UK and the USA. The survey asked for details of clotting tests, the use of genetic analysis and the use of global haemostatic assays in haemophilia A cases. The results show considerable variation in the laboratory methods used for the screening, diagnosis and monitoring of haemophilia A. There is variability in the techniques used even for long-standing, standardised assays such as the one-stage factor assay. There is marked regional variability in the use of molecular diagnosis. Assessment of haemophilia A requires accurate and sensitive assays. Some laboratories continue to rely on a single-factor assay in the diagnosis of non-severe disease, although cases with assay discrepancy may be missed by this strategy. Global assays are becoming important in the evaluation and management of patients. However, standardisation and the correlation with clinical outcomes require further study. Genetic diagnosis in patients with haemophilia remains underutilised in USA, possibly because of a lack of funding.