The 20-year-old girl we describe presented with myelofibrosis and systemic lupus erythematosus (SLE), which initially responded to treatment with corticosteroids but during a relapse 9 months later a bone marrow biopsy revealed no improvement in her myelofibrosis. As the cytotoxic treatments used to treat severe SLE may be associated with bone marrow suppression, it is important to consider the possibility of myelofibrosis complicating SLE, which, even when it is a presenting feature, may not readily respond to corticosteroids. When this girl was subsequently treated with high dose steroid and azathioprine her myelofibrosis went into remission.