Abstract: Simultaneous determination of factor VII activities in Autoplex and FEIBA was performed by amidolytic (VIIam) and one-stage clotting (VIIc) methods, to evaluate the presence and possible role of activated factor VII in these activated PCC preparations. As a tissue thromboplastin, monkey brain (monkey T. P.) and rabbit lung tissue thromboplastins (rabbit T. P.) were employed in both assay systems.In healthy subjects, the plasma level of VIIam was quite similar to and correlated well with that of VIIc, and was not significantly influenced by the kinds of tissue factor.The level of VIIc was significantly higher than that of VIIam in both preparations, showing that the ratio of VIIc to VIIam (VIIc/VIIam, factor VII activity ratio) was 13.3 in Autoplex and 4.8 in FEIBA. The difference of the values was more remarkable when monkey T. P. was used as the tissue thromboplastin reagent, showing 92.9 in Autoplex and 23.8 in FEIBA. These results suggest that some activated factor VII is contained in these two preparations, and may be playing an important role in the treatment of inhibitor patients with classic hemophilia.