We report a 71-year-old man who presented with severe subcutaneous and later psoas muscle haemorrhage in the presence of a raised white cell count and hepatosplenomegaly. A circulating factor VIII (FVIII) inhibitor was detected and bone marrow morphology confirmed the presence of a myeloproliferative/myelodysplastic disorder. Initial treatment with high dose FVIII followed by recombinant factor VIIa was unsuccessful. Haemorrhage was controlled by the administration of activated prothrombin complex concentrate (FEIBA; Baxter healthcare, CA, USA) in combination with prednisolone, cyclophosphamide and i.v. immunoglobulin. The inhibitor became undetectable 14 weeks after presentation. The white cell count responded initially to hydroxyurea and later to cyclophosphamide. There have been only two previous reports of acquired haemophilia A in association with myelodysplastic disorders and no previous report of an association with a myeloproliferative disorder.