In 2009 the International Stem Cell Banking Initiative (ISCBI) contributors and the Ethics Working Party of the International Stem Cell Forum published a consensus on principles of best practice for the procurement, cell banking, testing and distribution of human embryonic stem cell (hESC) lines for research purposes [1] , which was broadly also applicable to human induced pluripotent stem cell (hiPSC) lines. Here, we revisit this guidance to consider what the requirements would be for delivery of the early seed stocks of stem cell lines intended for clinical applications. The term 'seed stock' is used here to describe those cryopreserved stocks of cells established early in the passage history of a pluripotent stem cell line in the lab that derived the line or a stem cell bank, hereafter called the 'repository'. The seed stocks should provide cells with suitable documentation and provenance that would enable them to be taken forward for development in human therapeutic applications. WHO recommendations for the evaluation of animal cell cultures as substrates for the manufacture of biologicals and for the characterization of cell banks were updated in 2010 and provide a number of definitions and guiding principles that may apply to stem cells. The term 'cell bank' is used to describe a stock of vials or other containers of cells with consistent composition aliquoted from a single pool of cells of the same culture history (for other specific definitions see PAS 84 [2] and WHO [3] ).Three important assumptions have been made in the preparation of this document. First, that seed stocks of hPSCs are used as starting materials to make cell banks for use in clinical trials. The cell banks made within a clinical trial would need to be established according to Good Manufacturing Practice (GMP) in a facility with a relevant product manufacturing license. These banks would need additional risk assessment focused on the new banking process/reagents and the specific intended clinical application. Second, it has been assumed that undifferentiated pluripotent stem cells would not be inoculated into patients. Third, where feeder cells are used to culture hPSC lines, their cellular nature and intimate contact with the therapeutic cells means that they should be subject to similar risk assessment and banking procedures as applied to the hPSC cells.It is important to note that responsibility for establishing and updating national regulations for medicinal products relies on National Regulatory Authorities. Therefore, national requirements for cell therapy may vary considerably. Accordingly, it is not intended that this international consensus provides comprehensive guidance that will ensure compliance with requirements in any given jurisdiction. Rather, it is designed to aid the development of clinical grade materials by providing points to consider in the preparation of seed stocks of stem cell lines for use in cell therapy. It may arise that there are circumstances where it is not reasonably possible to meet specific procedures presented in this document. Where this is the case any alternative procedures should be justified and mitigate against any adverse consequences. Finally, this document could also serve as a useful reference to assist in the evaluation of potential sources of candidate cell lines for the development of cell-based medicines, and provide the links necessary to identify some of the key differences in regulatory requirements between countries.