A translator who embarks on the seemingly steep path of medical translation has two main obstacles: medical knowledge, and medical terminology. This post is about the latter. Medical terminology presents problems which are different from other specialised domains. This post presents the most obvious problems in determining the right medical terminology. It is not an extensive list; nevertheless, it should present a clear case for the difficulties translators encounter in translating medical texts. Though written mostly from the point-of-view of French to English translation, it can also apply to medical translation of all language pairs. Lastly, these issues can also apply to the practice of medical lexicography.