In response to extensive consultation with stakeholders, the European Pharmacopoeia (Ph. Eur.) Commission embarked upon the setting of public standards for therapeutic monoclonal antibodies with a pilot phase, exploring flexible concepts of standardisation of these complex biological medicines in an increasingly evolving multi-product market. Current Ph. Eur. initiatives focus on the development of “horizontal” standards to reflect key quality attributes and associated testing strategies, and to establish suitable common expectations and general methodologies applicable to a wide range/classes of mAbs. The rapidly growing number of TNF-alpha antagonists on the market has led to an increased variety of approaches to bioassay selection for assessing and comparing potencies of anti-TNF-alpha biologics and their biosimilars. Questions have been raised concerning the appropriate choice of potency assays for particular products and how they should be conducted, designed, analysed and applied. This presentation will outline the approach towards the development of a Ph. Eur. general chapter on potency assays for anti-TNF-alpha products; it will focus on the Ph. Eur. collaborative study undertaken to assess the suitability of various bioassay models to be applied as universal methods for assessing the TNF-alpha inhibitory effect. The conclusions from the study will be discussed, with considerations on bioassay performance and system suitability. Rationalisation of such methods would provide a better standardisation of the different products available and under development.