She says agents go from village to village, looking for girls whom they lure away with promises of marriage or a good job.
She says that, because many of the victims are poorly educated, they fall for the trick and when they come to the city they get locked in a brothel.
She says they get angry easily, they shout a lot and many of them just want to die.
She says she tries to encourage them to love themselves again, but that can take years of therapy.
Mental treatment may take years As well as treating victim's mental and physical injuries, the Somaly Mam Foundation provides further education and job training to help the girls find employment after they leave the center.
But the main aim is to teach the girls that their lives have meaning and that they can have a bright future.
She says that if she refused she was tortured with electric shocks or forced to eat hot chilies.
She says she had to receive more than ten clients a day and that most of them were drunk, smelled bad and were very violent.
She says she was approached by a man while playing outside.
He asked her to come over and talk to him, and before she knew it she was alone and being asked for sex.
Although some sex workers do the job to escape poverty, many of those working in brothels are victims of human trafficking who are held against their will and forced to work as sex slaves.
Founded by a former sex slave, The Somaly Mam Foundation was set up in 1996 to rescue and rehabilitate victims of human trafficking.