For the first time, Olympians competing in Athens this summer will be tested for the banned substance Human Growth Hormone (HGH).
The drug stimulates muscle-growth and was previously thought to be undetectable.
However, a research team from Southampton University in the UK has come up with a test, involving urine and blood samples being taken from random athletes within an hour after the end of their events.
In a two-stage testing process, scientists say that the samples will show if the athlete has taken HGH up to 84 days before the Games begin.