LGBTQ activists have welcomed the first time in South America that people who do not identify as male or female can tick a third box in their ID cards.
People who neither identify as male nor female in Argentina will be able to use "X" the gender field in their national ID document and passports starting Wednesday.
Argentina is the first country in South America to officially recognize nonbinary citizens.
The county's center-left government said it was joining countries such as New Zealand, Canada and Australia with its decision.
According to a notice published in the official gazette, applications for national ID documents will cover a variety of gender options, including nonbinary, unspecified and undefined.
Argentina's President Alberto Fernandez delivered the first three ID cards with the "X" format during an official ceremony.
"The state should not care about the gender of its citizens," Fernandez said. "There are other identities than men and women and they must be respected," he added.
Fernandez, who publicly champions his well-known drag queen son, has been an advocate of gender and sexual equality.
There are "a thousand ways to love, to be loved and to be happy," Fernandez said.
"The ideal will be when all of us are just who we are and no one cares about people's gender," he added. "This is a step we are taking and I hope one day we get to the point where IDs don't say if someone is a man, woman or anything else."
Argentina's LGBT Federation (FALGBT) hailed the "historic advance" of rights. "All identities are valid!" the group said on Twitter.
"Although the use of the 'X' is not completely inclusive in the recognition [of] the wide range of identities that exist, it is an important step on the way toward real equality of rights," FALGBT said in a statement.
Argentina is one of the most progressive countries in the region in terms of social reforms.
The South American country passed a law recognizing same-sex marriage in 2010. Two years later, it legally allowed gender identity change.
In June, lawmakers approved a 1% quota of public sector jobs to be reserved for transgender people.
fb/rt (AFP, Reuters, EFE)