This article studies the long term relationship between medical speech, on one hand, and translation practice on the other. The transfer from specialized knowledge between different people and cultures has usually been mediated by the praxis of translation from a language to another, especially since the Renaissance. The analysis of translated works gives us a report about the transmission, reformulation and transformation of knowledge, without forgetting the ideological factors that intervene in it, such as mechanisms of crossbreeding and domination. Besides the translators, other agents operate in the process: publishers, patronage or the reading public. Neither the texts, nor the diversity of genres which make up the medical speech, or the specialized terminology, nor the knowledge and the attitudes about medicine are independent of these translation processes that the author exemplifies with several cases documented in history.