Medical translation is a highly technical type of professional translations: it has always held a special position (Balliu 2005) and requires a specific training for both learners and teachers. In the Master’s degree in translation offered at the University of Lorraine, France, the training programme of future translators is based on grammar and linguistics taught in general translation classes. The first medical translation carried out by students and examined in classes is a French notice de médicament, that is a PIL or a product monograph. We first find that students feel uncertain about the words to use as the document contains technical vocabulary. Moreover translating modals may lead to uncertainties in students’ minds and copies. Traditional translation theories taught in France (Vinay and Darbelnet 1958; Chuquet and Paillard 1989; Quivy 2010) applied to medical texts show that these uncertainty zones remain. Beyond grammar and vocabulary prerequisites, training in medical translation requires other extralinguistic trainings, such as specific trainings in documentary resources, communicative strategies and medical phraseology. A PIL is a highly regulated document, following medical norms and containing medically approved information; it is written for a broad readership with sometimes limited medical literacy. The functionalist approach (Nord 1997/2008) encompasses all these criteria and is based on the communicative core function of the target text. If this approach is explored by teachers and then taught to learners, uncertainty zones in medical vocabulary and modals disappear; moreover the functionalist approach is particularly well-suited to medical translations (Montalt and Gonzáles Davies 2007)