The European Organisation for Research and Treatment of Cancer quality of life (EORTC QL) questionnaires are used in international trials and therefore standardised translation procedures are required. This report summarises the EORTC translation procedure, recent accomplishments and challenges. Translations follow a forward-backward procedure, independently carried out by two native-speakers of the target language. Discrepancies are arbitrated by a third consultant, and solutions are reached by consensus. Translated questionnaires undergo a pilot-testing. Suggestions are incorporated into the final questionnaire. Requests for translations originate from the module developers, physicians or pharmaceutical industry, and most translations are performed by professional translators. The translation procedure is managed and supervised by a Translation Coordinator within the EORTC QL Unit in Brussels. To date, the EORTC QLQ-C30 has been translated and validated into more than 60 languages, with further translations in progress. Translations include all major Western, and many African and Asian languages. The following translation problems were encountered: lack of expressions for specific symptoms in various languages, the use of old-fashioned language, recent spelling reforms in several European countries and different priorities of social issues between Western and Eastern cultures. The EORTC measurement system is now registered for use in over 9000 clinical trials worldwide. The EORTC provides strong infrastructure and quality control to produce robust translated questionnaires. Nevertheless, translation problems have been identified. The key to improvements may lie in the particular features and strengths of the group, consisting of researchers from 21 countries representing 25 languages and include the development of simple source versions, the use of advanced computerised tools, rigorous pilot-testing, certification procedures and insights from a unique cross-cultural database of nearly 40,000 questionnaire responses.