Since the second half of the nineteenth century, the growing development of the medico-hygienist movement and its insoluble combination with the eugenic movement have promoted in Chile the gradual introduction of institutional measures aimed at the knowledge, treatment and eradication of blenorragia, syphilis and soft canker, variants of so-called shameful diseases, which have been conceived as diseases of social importance since the 1920s. This article seeks to ascertain the medico-legal assessment of the transmission of these conditions, during the verification of sexual assaults classified as rape, in Santiago and Valparaíso, the main cities of the country, between 1890 and 1920. After considering the medical knowledge and moral perspectives from which treated infections and sexual offences were analysed, as well as their forensic assessment, the practical implementation of these provisions in judicial proceedings is analysed.