This report was produced at the request of the Secretary of State for Health in response to the withdrawal of an oral polio vaccine (OPV) in October 2000 in light of it containing bovine material and the negligible risks this entailed due to a rise in bovine spongiform encephalopathy (BSE) outbreaks. It examined the circumstances leading to the withdrawal and makes recommendations on the wider issues raised by these events. These include the need for the Medicines Control Agency to review its procedures for checking validity of information supplied by pharmaceutical companies, a published summary of advice on vaccination production by the Committee on Safety of Medicines and clear communication to the public and health care professionals on the links between vaccine manufacture and BSE.