UK Athletics will not ban an unnamed female athlete who tested positive for an anabolic steroid.
Her claim that there was a medical reason for the finding was accepted by both UK Athletics and the IAAF, the sport's worldwide governing body.
The athlete tested positive for the steroid 19-norandrosterone between April and the end of June 2004.
UK Sport, Britain's anti-doping body, investigated the decision and confirmed that no further action would be taken.
A UK Sport statement said: "The explanation and the analytical data has been reviewed in accordance with UKA procedures and has also been reviewed by the IAAF."
A UK Athletics spokeswoman confirmed 19-norandrosterone could occur naturally under certain circumstances.