As long as there has been competitive sport, there have been individuals who have sought to gain an advantage over their opponents by whatever means are available to them. Attempts to use "drugs" to influence the outcome of sporting competitions date back at least to Roman times and probably well before.

Nowhere has this been more so than in racing, probably because, until recent years, this has been the sport which has provided the only legal form of gambling in most countries. Horseracing, as we know it, has developed and gained enormously in popularity over the past few hundred years. Along with this development, the use of drugs to fix races became an increasingly difficult problem for the sport's administrators.

The drugs used by the horse dopers have largely reflected the pharmacological knowledge of the time and the methods used for their detection have closely followed the development of analytical chemistry. Each new drug is seen by the dopers as a new opportunity to cheat, whereas each new development in analytical chemistry provides a new way to police the sport.

New analytical methods have been so successful that deliberate cheating involving the use of illegal "go-fast" drugs and "stoppers" is now relatively rare and restricted to isolated incidents. More usually, the drugs detected nowadays result from inappropriate use of therapeutic medications or attempts to manipulate levels of substances such as hormones and electrolytes which occur naturally in the animal's system.

In the last twenty-five years, it has been the mass spectrometer which has , more than any other instrument, provided the analyst with the means to severely curtail the use of illegal substances. This paper will discuss the development of racing chemistry from the use of simple animal-based tests to today's automated electronic technology.