Taiwan is voting on whether to become the first place in Asia to legalise gay marriage.
The vote comes after Taiwan's top court ruled in favour of same-sex marriage, giving parliament two years to amend existing laws or pass new ones.
However, surveys released in the last week suggest the country will vote against the change.
The issue is one of 10 that voters are being asked to consider, including one which is inflaming tensions with China.
Voters are being asked what they want to be called at the 2020 Tokyo Olympics: Taiwan or Chinese Taipei.
Currently, Taiwan competes as Chinese Taipei, the name agreed with China in the 1980s.
This is because Taiwan's status is sensitive. The island has been self-ruling since 1949, but China regards it as a breakaway province it will reunite with one day.
The referendums are running alongside local elections. Results are expected late on Saturday.
What are voters being asked about same-sex marriage?
The issue is actually the subject of two separate referendums on Saturday, which have been put forward by rival groups.
Conservative groups have asked whether marriage should be legally defined as between a man and a woman, while LGBT activists have put forward one for equal marriage rights.
The two sides have also put other issues to voters, including rival questions on education around LGBT issues in schools.
According to a survey carried out by the Taiwan Public Opinions Foundation, 77 percent of respondents believe marriage should be legally defined as between a man and a woman.
The government has said the vote will not affect it bringing in the changes required by the court ruling more than 18 months ago.
But campaigners fear it will mean the eventual legislation will be weaker.
"We hope that love and equality will win," Suki Chung, East Asia campaigner at human rights group Amnesty International told news agency AFP.
"However, if the opposite happens then the government must not use the result as cover to water down same-sex marriage proposals."