Had the proposed measure been passed, it would have legalised a woman's right to seek an abortion in the 14th week of her pregnancy. The bill had narrowly passed in the lower house in July.
Argentine senators on Thursday voted against legalising abortion in the homeland of Pope Francis, dashing the hopes of women's rights groups.
The senate voted 38 to 31 against the proposed measure, which would have legalised a woman's right to seek an abortion in the 14th week of pregnancy.
The bill had narrowly passed in the lower house in July.
Families and clergy in baby-blue bandanas gathered outside the congressional palace as the result came in just before 3 am, waving Argentine flags in support of the Catholic Church's anti-abortion stance in Pope Francis' home country.
TRT World's Monica Yanakiew reports.
Country with 'family values'
"What this vote showed is that Argentina is still a country that represents family values," said anti-abortion activist Victoria Osuna.
Current Argentine law only permits abortions in cases of rape, or if the mother's health is at risk.
Abortion rights supporters, clad in green bandanas that have become a symbol of the movement, danced to drum lines and swarmed the city’s streets to the end, despite a biting wind and cold rain.
Many had camped in front of Argentina's National Congress since Wednesday night.
"I’m still optimistic. It didn’t pass today, but it will pass tomorrow, it will pass the next day," said abortion rights supporter Natalia Carol, 23. "This is not over."
Ahead of the senate vote in Argentina, President Mauricio Macri called the debate "a win for democracy." Macri said he was personally against abortion, but would sign the bill if it passed.
Argentina's abortion rights movement, backed by feminist groups galvanised in recent years to stop violence against women, argued that the bill would end unregulated abortions that government data show as the leading cause of maternal deaths.
There are at least 350,000 illegal abortions in Argentina every year, the Ministry of Health estimates, though international human rights groups say the number may be higher.
The move to legalise abortion in Argentina is a "public health and human rights imperative," said New York-based Human Rights Watch.
"Just because the bill got shot down, it will not stop the movement," said Paula Avila-Guillen, a director of Women's Equality Center, an abortion rights advocacy group.
"We will be there at the next legislative opportunity."
Uruguay and Cuba are the only Latin American countries that now have broadly legalised abortion.
In Brazil, the supreme court is set to consider whether current law, which allows terminating pregnancies only in cases of rape, foetal deformation or when the mother’s life is in danger, is unconstitutional.
But passing a pro-abortion law will face hurdles in Brazil's increasingly conservative congress, with a growing evangelical Christian caucus that is staunchly opposed.
Women's rights advocates, however, hope that a more liberal judiciary in Brazil will at least decriminalise abortion to help avoid deaths from botched terminations in a country where hundreds of thousands of women resort to clandestine clinics each year.