This article presents the findings of a study about the history of aversion therapy as a treatment technique in the English mental health system to convert lesbians and bisexual women into heterosexual women. We explored published psychiatric and psychological literature, as well as lesbian, gay, and bisexual archives and anthologies. We identified 10 examples of young women receiving aversion therapy in England in the 1960s and 1970s. We situate our discussion within the context of post-war British and transnational medical history. As a contribution to a significantly under-researched area, this article adds to a broader transnational history of the psychological treatment of marginalised sexualities and genders. As a consequence, it also contributes to LGBTQIA+ history, the history of medicine, and psychiatric survivor history. We also reflect on the ethical implications of the research for current mental health practice.