The article discusses terminology related problems faced by interpreters working in the EU institutions. Interpreters have various sources of terminology at their disposal: dictionaries, data bases, glossaries, written translations and, last but not least, their delegates. Since the main task of interpreters is to ensure smooth communication in a meeting taking place in a multilingual and multicultural environment, interpreters tend to use terms preferred by delegates. Problems arise due to the fact that often there is no consistency between terms coming from different sources. In order to facilitate communication and consolidate and harmonise terminology closer co-operation is needed between terminologists and experts who most of the time work autonomously and often arrive at different terms for one and the same concept.