An informal meeting was held at the National Institute for Biological Standards and Control (NIBSC), Potters Bar, U.K. on 24 August 1989 between representatives from industry, the World Health Organisation (WHO) and NIBSC to discuss issues related to the use of human diploid cells (HDC) in virus vaccine production. This record of the discussions and concensus views which emerged are provided to stimulate consideration by a wider audience. A list of participants is given in the Appendix.