Abuse of hormones by sportsmen or sportswomen might lead to some serious health consequences for the individual user. Such abuse also damages the very spirit of sport, cheating fellow athletes, the officials and spectators. Where hormone findings cause most controversy is with endogenously produced substances. Some hormone findings might be indicators of a medical condition, and it requires sensitive handling to discover the facts. Examining the prevalence of hormone abuse using a theoretical perspective on ethics permits a philosophical study of the dilemmas facing sport, and a clearer identification of the issues that science can help sport to resolve. This paper looks at the way in which rules on doping have evolved in an attempt to set out the ethical standards that should apply and to discuss how some sportsmen and sportswomen have worked around the rules, challenging them to the extent that the anti-doping system itself is questioned. The data emerging from the testing programmes give one guide to the actual prevalence of hormone findings. However, as not all findings may constitute doping offences this cannot be said to be the definitive guide to the extent of hormone abuse. Use of hormone medications with or without a therapeutical indication further complicates the disciplinary process. Sensitive management of hormone findings is absolutely necessary to avoid accusations of doping or embarrassing breaches of confidentiality when the origin may be a serious medical condition. Because hormone findings require careful consideration, the door is open for the anti-doping system to be exploited by unscrupulous scientists, raising challenges that test the limits of credibility. Sex, alcohol and decomposition are arguments that have been put forward to explain findings. A close partnership between scientists and sport is called for to avoid the athlete becoming a victim of the rules that are intended to protect sport.