The case of a 52 year old woman with chronic severe refractory thrombocytopenia is presented. Over a three year period, her platelet count was persistently less than 20 x 10(9)/litre (normal range, 150-400). She required repeated hospital admission for management of bleeding and received multiple blood transfusions. She was given repeated courses of steroids, immunosuppression, immunoglobulin, and splenectomy, without success, in an attempt to stop the chronic blood loss. Eventually, she was found to be profoundly hypothyroid. On correction of her thyroid deficiency the platelet count returned to the normal range and all bleeding stopped. The platelet count remains in the normal range three years later.