A significant number of psychiatrists and therapists are trying to help lesbian or gay patients become heterosexual, according to research.
This is despite a lack of evidence that such treatments can be beneficial or even safe, the study in the journal BMC Psychiatry said.
The research found that one in six of the 1,400 mental health professionals surveyed reported having helped at least one patient curtail their gay, lesbian or bisexual feelings.
One in 25 psychiatrists or therapists said they would try to treat someone who was having such emotions if asked today.
Professor Michael King, from University College London, who worked on the study, said: "There is very little evidence to show that attempting to treat a person's homosexual feelings is effective and, in fact, it can actually be harmful. So it is surprising that a significant minority of practitioners still offer this help to their clients."
One anonymous professional who took part in the study said they would help a patient if they held a religious belief that forbade homosexuality. Another said: "The individuals I have worked with have all been very unhappy about their sexuality and wish they were heterosexual."
Professor King now wants to raise awareness amongst those trying to treat homosexuality.
He added: "The best approach is to help people adjust to their situation, to value them as people and show them that there is nothing whatever pathological about their sexual orientation. Both mental health practitioners and society at large must help them to confront prejudice in themselves and in others."
Academics at St George's, University of London, helped compile the research, which was funded by the Wellcome Trust. A new website - www.treatmentshomosexuality.org.uk - is also being set up where those who have received such treatment, as well as those who have administered it, can provide their own views.
Derek Munn, director of public affairs at Stonewall, the gay and lesbian equality organisation, said: "So-called gay cure therapies are wholly discredited. The conclusions of this research are a welcome reminder that what lesbian and gay people need is equal treatment by society, not misguided treatment by a minority of health professionals."
