The International Day Against Homophobia, initiated by a Quebec organization, will be celebrated in more than 50 countries this weekend, decrying discrimination against gays and lesbians.
"There are 192 countries at the UN, and half of them still ban homosexuality, notably most countries in Africa, in Asia and Arab countries," said Laurent McCutcheon, president of Quebec's Emergence Foundation, an activist group behind the annual fete.
Five countries punish homosexual acts with death, said its website.
In 2003, Emergence launched a national day against homophobia in Canada, which caught on internationally in the past three years.
May 17 was chosen because it was on this date in 1990 that the World Health Organization removed homosexuality from its list of mental illnesses. The acronym IDAHO is often used to delineate this day.
"These last three years, we've seen new initiatives all over the place," McCutcheon told AFP.
"But there's still a lot of work to do," he said.
Only 67 countries signed the first ever statement on sexual orientation and gender identity at the UN General Assembly last year, sponsored by France and the Netherlands.
"The Vatican didn't even want to sign it," McCutcheon noted.
"Russia also seems to be a hard nut," he said, noting a series of violent attacks on gays, lesbians and transgender people in the country.
Earlier, Russia upheld a ban on gay pride celebrations set to coincide on Saturday with the Eurovision Song Contest finale in Moscow, leaving the door open to more violence.