In this work on medical translation, the author first makes a general comparison of French and English usage, analysing the various aspects: borrowings, calques, transpostion, modulation, equivalence, adaptation. Examples are given of faux amis, whether semantic, stylistic or phraseological. Secondly, the author discusses problems specific to medical translation, which are divided into three main categories: differences in usage, standard terms and medical acceptations and terminological differences.