Patients with Turner's syndrome are at risk of X-linked recessive disorders. We report a case of a young girl with Turner's syndrome with persistent mildly abnormal coagulation studies associated with a mild to moderate bleeding diathesis. The abnormalities were initially attributed to intrahepatic cholestasis and were partially responsive to vitamin K. After an interval of several years an episode of unexplained iron deficiency anaemia prompted re-investigation of the mild coagulopathy. Disproportionate reduction in the factor IX concentration and restoration of haemostasis with factor IX concentrate lead to a revised provisional diagnosis of mild haemophilia B which was subsequently confirmed by sequencing the factor IX gene.