This paper is concerned with a comparison of medical texts in English and Spanish and their lexical characteristics. According to the authors, although there are clear similarities between the two languages, it is differences like the use of anglicisms or the preference of technical terms in the case of the Spanish texts that this paper tries to highlight. It should be noted, however, that one aspect in which both languages coincide is the use of metaphorical expressions like trunk (“tronco”), abdominal wall (“pared abdominal”), bloodstream (“chorro sanguíneo”), visual field (“campo visual”), nerve roots (“raíces nerviosas”), sperm head (“cabeza del espermatozoide”), among others. In these cases, we have identical metaphors in English and Spanish although, according to the authors, there are other expressions in which the metaphorical reference has been slightly changed, as in scarlet fever (“escarlatina”).