The potency assay of human coagulation factor VII concentrate preparations as described in the EuropeanPharmacopoeia (Ph. Eur.) requires a reference preparation calibrated in International Units (IU). The current Ph. Eur.Biological Reference Preparation (BRP) batch 1 was established in 2005 during an international collaborative study. Ithas an assigned potency of 8.2 IU/vial for the chromogenic assay method. Stocks of this BRP are dwindling and areplacement batch needs to be established.A candidate material was produced by a manufacturer from a plasma-derived concentrate preparation, with the sameformulation and approximately the same potency, in the interest of continuity. The candidate material fulfilled therequirements of a BRP with regard to precision and homogeneity of fill, residual water content and stability. Thepotency of the candidate BRP (cBRP) was determined using chromogenic assays as required by the Ph. Eur. andin-house clotting assays in an attempt to assign a potency for both methods, as is the case for the current batch.The statistical model used for most laboratories was the maximum likelihood of the parallel line model using alogarithmic transformation of the responses. In the chromogenic assay, a potency of 9.9 IU/vial (± 1.8 %) was obtainedfor the cBRP with a very good consistency between laboratories. The results from the clotting assay, however, wereless homogenous and yielded consistently higher results (13 IU/vial ± 12 %), probably due to a higher activatedfactor VII (FVIIa) content than in the current BRP (3 % as compared to 0.3 %). Due to the large difference between thevalues obtained with the 2 different methods, it was not possible to reconcile the outcomes with each other. On the otherhand, the uncertainty observed with the clotting assay method was quite large and seemed questionable for a referencepreparation. Therefore the use of BRP batch 2 as a reference for the clotting assay method is not recommended.Nevertheless, the results of the study showed that the candidate BRP (cBRP) is suitable as a reference standard for thechromogenic assay according to the Ph. Eur. general chapter 2.7.10 Assay of human coagulation factor VII. It wasadopted by the Ph. Eur. Commission in December 2009 as an official Ph. Eur. BRP for human coagulation factor VIIconcentrate with an assigned potency of 9.9 IU/vial.