This chapter deals with the legal and ethical issues surrounding medical research, including studies conducted upon children and upon adults who lack the capacity to consent. Medical research allows patients both present and future to be offered the most effective and efficacious treatment possible for any given condition. The Declaration of Helsinki underpins the ethical and legal framework within which medical research is conducted throughout the world. The General Medical Council (GMC) has issued very clear and comprehensive guidance on the role and responsibilities of doctors in relation to research. The GMC issues specific guidance which acknowledges that children and young people are vulnerable members of society. The principles of research upon human subjects particularly informed consent, apply equally to tissue-based research. The Central Office for Research Ethics Committees works on behalf of the Department of Health in England and co-ordinates the local and multicentre research ethics committees across the country.