Vijay Singh has been cleared of doping by the PGA Tour despite admitting using a banned substance.
Fiji's former world number one told US magazine Sports Illustrated he used deer antler spray, which contains small amounts of growth hormone.
But the World Anti-Doping Agency told the Tour it does not contain sufficient quantities to break the rules.
"The Tour deemed it only fair to no longer treat Mr Singh's use as a violation," said a statement.
The spray contains IGF-1, a natural anabolic hormone that stimulates muscle growth, which is on the banned list set by Wada.
What is deer antler spray?
- The spray, sold by SWATS (Sports With Alternatives to Steroids), is harvested from the antlers of New Zealand deer.
- Deer antler spray and pills contain small amounts of deer IGF-1 (Insulin-like Growth Factor-1) - a growth hormone.
- Research has shown that velvet deer antler improves heart strength, stamina, joint health, muscle and strength development plus athletic performance.
- Christopher Key of SWATS was quoted in Sports Illustrated as saying: "The antlers are the fastest-growing substance on planet Earth... because of the high concentration of IGF-1. We've been able to freeze dry that out, extract it, put it in a sublingual spray that you shake for 20 seconds and then spray three [times] under your tongue. This stuff has been around for almost 1,000 years."
In the Sports Illustrated article published in January Singh, 50, was quoted saying he used the product "every couple of hours... every day".
He subsequently released a statement saying: "While I have used deer antler spray, at no time was I aware that it may contain a substance that is banned under the PGA Tour anti-doping policy.
"In fact, when I first received the product, I reviewed the list of ingredients and did not see any prohibited substances."
The PGA Tour was forced to treat Singh's admission as a violation of anti-doping policy and a sanction was issued.
Singh appealed, and on 30 April, Wada wrote to the Tour to confirm it no longer considers the use of the spray to be prohibited unless a positive test occurs.
The Tour statement added: "Since his initial quote was made public, Mr Singh has cooperated with the Tour investigation and has been completely forthcoming and honest.
"While there was no reason to believe that Mr Singh knowingly took a prohibited substance, the PGA Tour Anti-Doping Program clearly states that players are responsible for use of a prohibited substance regardless of intent."
The Tour added that it will increase its educational initiatives to remind players of the anti-doping policy, and highlight the risk of using products without fully understanding what they contain.
Since drug testing was introduced in golf in 2008, only one player has been banned for violating the doping code.
American journeyman pro Doug Barron received a one-year suspension after failing a drugs test at the St Jude Classic in 2009.
Barron was taking Lyrica as a substitute for propranolol, a banned substance and exogenous testosterone, which he received by an injection from a doctor.
He had been prescribed propranolol since the age 17 but an earlier attempt to gain a medical exemption had been denied by the Tour.
Singh spent 32 weeks as world number one between 2004 and 2005, won the Masters in 2000 and the 1998 and 2004 PGA Championship.