A new case with the abnormal factor X (factor X Friuli) coagulation disorder is presented: a 32-year- old female who was born outside Friuli and who complained of a bleeding tendency since childhood. The main laboratory features are prolonged prothrombin time, prolonged partial thromboplastin time, abnormal thromboplastm generation and normal Stypven-cephalin clotting time. The prothrombin time and the thromboplastin generation were corrected by the addition of normal serum. Factor X was low only when assayed using whole tissue or partial thromboplastin. It was normal using the Stypven-cephalin mixture. The cross-over electrophoresis showed a normal factor X band in the patient’s plasma, whereas no band was present in Mr. Stuart’s plasma. The father and a cousin of the patient are heterozygotes for the abnormality. This is the first family reported to have the abnormal factor X (factor X Friuli) disorder outside Friuli.