This paper presents relevant issues that have been considered in the design and development of a general purpose lemmatiser/tagger for Basque (EUSLEM). The lemmatiser/tagger is conceived as a basic tool for other linguistic applications. It uses the lexical database and the morphological analyser previously developed and implemented. We will describe the components used in the development of the lemmatiser/tagger and, finally, we will point out possible further applications of this tool. 1. Introduction An automatic lemmatiser/tagger is a basic tool for applications such as automatic indexation, documental databases, syntactic and semantic analysis, analysis of text corpora, etc. Its job is to give the correct lemma of a text-word, as well as its grammatical category. This project is being carried out by two entities: a group of the Computer Science Faculty of The Basque Country University and UZEI (1), an association that works on Basque terminology and lexicography. It's not the fi...