Transgender athletes will be barred from competing in women's golf tournaments organised by the R&A from the start of next year.
The R&A has drawn up new guidelines following what it said was an "extensive consultation" last year with medical and scientific experts.
In a statement the R&A said: "The evidence shows that golf is a gender-affected sport in which male puberty confers a performance advantage.
"From the start of 2025, a golfer entering female professional and elite amateur championships organised by The R&A must have been female at birth or transitioned to female before the onset of male puberty to be eligible to compete.
"Players assigned male at birth and who have experienced male puberty are ineligible to compete in these events, but can enter male professional and elite amateur championships organised by The R&A."
The ruling brings the R&A into line with new policies established by both the LPGA and the USGA, both of which preclude players who have gone through male puberty from playing in their events.
R&A chief executive Martin Slumbers said: "We have carefully reviewed the best available medical and scientific advice relating to participation in elite and scratch level golf competitions by transgender athletes and decided that updating our entry conditions to preserve fairness in our female professional and elite amateur championships is the right thing to do.
"While we believe that golf should be open to all and are committed to developing the sport, we recognise that we have a duty to ensure that in our elite competitions players can compete fairly and equally."