Medical and pharmaceutical texts are full of references to chemical compounds, active ingredients and drugs. Guidelines will be given to recognise them, to translate them, if they should be written in upper- or lowercase, if they should or should not have an article, to know how to use hyphens in them or when words must be juxtaposed or not. By following the procedures given, an acceptable Spanish translation can be generated even if the translator is not a skilled chemist or pharmacist.