Homosexual acts were illegal in Ireland until 1993. Between 1962 and 1972 there were 455 convictions of men for crimes such as ‘indecency with males’ and ‘gross indecency’. Homosexuality was regarded as a mental illness by the American Psychiatric Association until 1973 and by the World Health Organisation until 1990. ‘Treatment’ provided in various countries, including England and Northern Ireland, included psychotherapies (such as psychoanalysis) and ‘aversion therapies’ involving delivering emetic medication or electric shocks to homosexual men as they viewed images of undressed males; administration of testosterone followed by showing films of nude or semi-nude women; and playing tape recordings outlining the alleged adverse effects of homosexuality and alleged benefits of heterosexuality. In Ireland, homosexuality was regarded as a sexual deviation throughout the 1960s and some psychiatrists were involved in court proceedings and ‘treating’ homosexual persons with psychotherapy. Although there are some suggestions that ‘aversive therapies’ were used for homosexuality in Ireland, there is currently insufficient primary evidence to clarify this further. The history of psychiatry’s attitude to homosexuality is revealing for what it shows of the changeability of psychiatric diagnostic practices over time, and the extent to which certain psychiatric diagnoses are subject to social, political and various other influences. There is a strong need to enhance mental health services for lesbian, gay, bisexual and transgender persons who experience mental health problems.