The aim of this paper is to present a lexical database of English collocations used in scientific language, which is being built in three Spanish universities (Barcelona, Illes Balears and Leon) and is mainly intended for the Spanish-speaking scientific community. The shortage of specialized dictionaries providing contextual information on the grammatical and collocational patterns in specific registers prompted the onset of this project. Our database is based on the analysis of a corpus of written texts in the areas of biology, biochemistry, and biomedicine, and provides the grammatical, semantic, and collocational information necessary for the correct and precise use of each term in scientific discourse. The paper describes the steps followed in the creation of the data base and it includes the case study of one of its entries.