This article challenges the distinction the law draws between male and female. It focuses on the legal and medical treatment of intersexual people. Analysing the nature and rate of intersexuality it argues that there is a significant number of people who cannot be described as either male or female and instead exhibit a range of sexual characteristics. Until recently the law and medicine have insisted that intersexual people should be categorized as either male or female. Surgery was performed to ensure that they had the appearance assumed to be the ‘norm’ for a man or woman and the law followed this medical assignment of sex. Over the last couple of years the established medical practice and the legal treatment have been challenged. This article discusses the nature of these challenges and argues that there is a strong case for rejecting the traditional legal and medical approach to intersexual people. Cosmetic surgery on intersexual babies should be delayed until the individual is old enough to be able to choose their own sexual identity, which may be neither male nor female. The insistence that every person must either be male or female is no longer supportable in medical or social terms and a much wider range of sexual identities must be recognized by the law.