Many professional and amateur sports including track and field, weight-lifting, boxing, canoeing, professional baseball and professional cycling have suffered scandals involving steroids and human growth hormone (HGH) and have done so for many years.1^–4 It seems self-evident that the use of steroids and HGH is a problem. The amount of media and political attention paid to steroids and other pharmacological forms of enhancement in sports, such as the use of blood doping and stimulants, suggest that biochemical enhancement is one of the greatest moral problems the world faces.

Well, OK, upon deeper reflection, the challenge of getting the steroids out of bicycle racing is not on the same moral plane as eliminating poverty or AIDS. Still, many people all over the world seem to think that the latest generation of performance-enhancing substances threatens the very integrity of sport. There has been a burst of writing in recent years making precisely this case and the budget and clout of the World Anti-Doping Agency (WADA) and similar policing agencies are growing, reflecting the view that chemical enhancement and fair competition cannot coexist.

In one sense, the argument that the current techniques for enhancing sports performance threaten sport is irrefutable. Synthetic steroids are dangerous. HGH in large amounts can be too. There is a real need to protect children who admire athletes, so as to prevent them from taking serious risks with their health in imitating what their idols do or, in a few instances, from being forced by their own parents to engage in risky behaviour in order to succeed in athletics.

But, what if biomedical science could put the safety issue aside? Someday, probably soon, there will be drugs that do what steroids do without any real risk of harm to the user. Forms of gene therapy are …