A report by Human Rights Watch says gay and transgender people in Turkey are subject to "endemic abuses", and calls on the government to act to protect them.
The BBC's Sarah Rainsford met some of the victims.
"This is my first photograph as a transsexual," a woman tells me, in her flat in back-street Istanbul.
She points to a snapshot of herself with long-flowing hair and thick make-up. On the opposite page of the album, a man with a moustache reminds her
how she used to be.
Smoking heavily, the woman - who asks me not to use her name - tells me she grew up as a man in the conservative east of
Turkey. She moved to Istanbul in her 30s, where she finally felt able to live as a woman.
"It's all I wanted," she says. "I used to dance as a woman and see the image of a man in the mirror and that upset me."
'Systemic violence'
But she has paid a heavy price for her transformation.
Once a businessman, she is now a sex-worker because no-one else will employ her. And like many transgender prostitutes here, she is a frequent
victim of violence - mostly from the police.
"I've been beaten many times," she shrugs.
"The more people are seen to be claiming their political rights, the more there is a backlash from society and the police" Scott Long, Human Rights Watch
"Once, I was walking down the street and the police said 'don't pass!'. Then two more came, they dragged me into the basement of the police station
and they hit me in the face and beat me so badly I had to live for 15 days with an extremely swollen head."
Her experience is typical of those documented by Human Rights Watch in its latest report.
It describes this type of violence as "systemic" in Turkey and records a wide range of abuses on the streets, in the family and from the police.
The BBC asked Istanbul police and the governor's office to comment. Both declined.
"Things were tough before, but they're getting worse," says Demet, who has been fighting for the rights of transgender people like herself for two decades or more.
Gay men face hostility even in relatively liberal Istanbul
"The police are making it harder for us to work on the streets. They're closing down the houses we use. They even banned us from walking past the
police station. We never had that before."
Demet blames the rise to power of a conservative, religious government - bringing bureaucrats to match.
Others point to the highly patriarchal nature of society here.
Transgender women are singled-out for the worst abuse, as the most visible. But many gay men and lesbians recount how difficult it is to be
"out" even in relatively liberal Istanbul.
Emrecan recently had a full beer bottle thrown at him and a friend on their way home from a gay club.
"It was very very scary for me," he recalls.
"It brought back memories of when I was badly beaten as a student. It took me a very long time to get over that. I had to actively work on being on
the streets without fear."
Uneasy defiance
Whilst Turkey's democratisation - and the EU accession process - have encouraged some to be more open about their sexuality, that could have a
flip-side.
"One thing we have learned is that visibility breeds violence," says Scott Long, of Human Rights Watch.
"My message is that we are here, living with you, get used to it" Esmeray, Transsexual stand-up act
"The more people are seen to be claiming their political rights, the more there is a backlash from society and the police," he says.
That certainly seems true for Lambda.
Tucked above a tattoo parlour, the only support group in Istanbul for lesbian, gay, bisexual and transgender people is a place where they can
relax, be themselves and be safe.