Around 400 people packed into the ballroom of a Yangon hotel late Thursday for an evening of performances, speeches and music to mark the International Day against Homophobia and Trans-phobia, an AFP reporter said.
"I'm very happy to be with the same group of people," gay make-up artist Min-Min told AFP. "In the past we didn't dare to do this. We've been preparing to hold this event for a long time... and today, finally it happens."
Same-sex relations are criminalised under the nation's colonial penal code, and although it is not strictly enforced, activists say the law is still used by authorities to discriminate and extort.
Celebrations were due to take place in four cities across Myanmar, said Aung Myo Min, an organiser from the Human Rights Education Institute of Burma.
Unlike gay pride events in more liberal countries, there will be no parade.
Instead, music, plays, documentaries and talks by authors were set to mark the occasions in Yangon, Mandalay, Kyaukpadaung and Monywa, Aung Myo Min said, adding that the events had been officially sanctioned.
"In the past a crowd of people at this kind of event would be assumed to be against the government -- taking part in something like a protest," he said.
"Now LGBT (lesbian, gay, bi-sexual and transgender) society has courage... and they dare to reveal their sexual orientation."
Totalitarian politics along with conservative religious and social values have conspired to encourage many gay people to keep their sexuality hidden in Myanmar, formerly known as Burma.
Attitudes contrast markedly from neighbouring Thailand, where a lively gay and transsexual scene is a largely accepted part of society, which -- like Myanmar -- is mainly Buddhist.
But dramatic political change since the reformist government of President Thein Sein came to power last year is rippling out to wider society.
Calling on the government to repeal laws criminalising gay sex, Aung Myo Min said taking part in an international event would empower Myanmar's gay population.
"They will have more courage to reveal their sexuality," he said.
"If we don't discriminate against them and respect that diversity, the world will be more beautiful than now."
The past taboo on homosexuality in Myanmar has restricted awareness of sexual health among the gay population.
In some areas, including Yangon and Mandalay, as many as 29 percent of men having sex with men are HIV positive, according to a 2010 report by the Joint United Nations Programme on HIV/AIDS.