Gene therapy may be the next major advance for treatment of many diseases, and severe haemophilia (an inherited deficiency of coagulation factor VIII or IX) is a useful model. Progress in gene therapy has been slowed down following fatal multi-organ failure during an adenovirus vector trial for ornithine-transcarbamylase deficiency and two episodes of leukaemia in a retroviral vector trial for severe combined immunodeficiency trial. A small number of early haemophilia clinical trials are in progress or reported. This paper considers ethical and statutory issues related to gene therapy for severe haemophilia within the UK and how these can be addressed through a well-established national network of haemophilia centres. It is likely that these issues will be relevant to clinicians considering gene therapy for other diseases.