Little attention has been paid so far to keywords and lexical bundles used in the English language typical of the pharmaceutical field. Conducted from a register-perspective (Biber 82 Conrad, 2009), this exploratory and descriptive research is intended to fill in the gap in corpus linguistics studies on phraseology and register variation within written English pharmaceutical discourse. More specifically, this empirical study presents a corpus-driven description of the use and functions of keywords (top-50 by keyness) complemented by a similar description of lexical bundles (top-50 by frequency) used across samples of patient information leaflets, summaries of product characteristics, clinical trial protocols and chapters from academic textbooks on pharmacology, all collected in a purpose-designed corpus. The results revealed salient links between situational, linguistic and functional features of the four pharmaceutical registers under scrutiny and showed that patterns of language use differ considerably due to topic- and function-related differences between the text types, despite their dealing with a similar theme, namely with medicines or medicinal products. Although primarily intended as descriptive, the data presented in this paper may have significant pedagogical value, notably with respect to teaching ESP to students and practitioners in the pharmaceutical field. (C) 2014 Elsevier Ltd. All rights reserved.