Transgender people can now officially apply for a certificate to recognise their acquired gender.
It comes after Ireland's new laws on gender recognition took full effect today.
Under the Gender Recognition Act, anyone can apply to the Department of Social Protection looking to have their acquired gender recognised by law.
Dr Lydia Foy, who fought a lengthy court case to have her new gender recognised, says it's a historic day.
She said: "We are delighted, the trans community. In the hopes, in the firm conviction now, I have my application form ready to be completed.
"In the hopes that nobody in Ireland will have to go through such pains and such a long-winded approach to the law."
Broden Giambrone of the Transgender Equality Network of Ireland has paid tribute to the campaigners who made the law a reality.
He said: "This legislation is incredibly progressive, it's very humane and it's going to affirm the rights of transgender people in this country.
"I think this is one of the most momentous days in the trans community's history.
"Of course, we wouldn't be here without Dr Lydia Foy and FLAC, Michael Farrell who have taken a 22-year journey to get to this point."