This study investigates the formation of the concept of male homosexuality in medical discourse from the mid-19th century to the interwar period, in Europe and Greece. Considered for centuries as a sin and a criminal offense, male homosexuality was pathologized in the 19th century and became the subject of a new medical specialty emerging in northern and central Europe: sexology. The central questions, explanatory frameworks, and therapeutic proposals developed within the European sexological traditions are presented, as well as the connection of representatives of sexology with the homosexual rights movement. In contrast, in Greece, despite its adherence to the European medical model, there is no development of sexology up to the interwar period. Special studies on homosexuality are absent from Greek-language literature, while brief related references in forensic and psychiatric manuals and articles present human sexual life as inextricably linked to reproduction, and same-sex sexual relations exclusively as a disease. Additionally, in the social field, a Greek movement for homosexual rights is absent. Finally, some interpretations for the Greek differentiation are formulated.