OBJECTIVES: The objective of the study was to translate and linguistically validate the Insulin Treatment Satisfaction Questionnaire (ITSQ) for use in 18 countries in 22 languages, including Czech, Greek, Hungarian, Romanian, Russian, Serbian, Slovenian and Turkish. The questionnaire was developed in 2003 and was designed to assess the satisfaction with insulin treatment by patients with diabetes. METHODS: The methodology employed was: 2 forward translations and their reconciliation, 2 back translations, back translation review, client affiliate review, linguistic validation interviews with 5 patients with diabetes and 2 proof readings. RESULTS: While the majority of wording was easily agreed upon, certain words and phrases were more troublesome. Issues and solutions included: “How much bother” was difficult to render in some languages. In Bulgarian, for example, this was translated as “How difficult”, with the context implying “being annoying and causing frustration”. In Romanian, “burdensome” was rendered as “troublesome”, and “fatigue” was rendered as “extreme tiredness”, as there is no direct translation of these English terms. Russian patients could not understand the direct translation of “avoid” (as in “avoid symptoms of hyperglycaemia”) – this was revised to read “will not have”. Slovenian patients could not understand the translation of “stability” (as in “stability of blood sugar levels”) – this was revised to a word meaning “permanency” or “invariability”. CONCLUSION: The ITSQ has been translated and linguistically validated and is now available for use in 18 countries (including 8 Eastern European nations) and in 22 languages. This project has also highlighted the importance of linguistic validation interviews.