OBJECTIVES: The Nighttime Symptoms of COPD Instrument (NiSCI) and Early Morning Symptoms of COPD Instrument (EMSCI) were developed to support treatment benefit endpoints in global clinical trials.  Translations that were conceptually equivalent to the English source version and easily understood by the target country populations were required. The purpose of this study was to translate and assess conceptual equivalence of the NiSCI and EMSCI for use in 14 countries: Austria, Bulgaria, Canada, Czech Republic, France, Germany, Hungary, Italy, Lithuania, Netherlands, Poland, South Africa, Spain, and United Kingdom. METHODS: The NiSCI and EMSCI were translated following ISPOR guidelines for linguistic validation of PRO measures (Wild et al., 2005) using the universal approach discussed in the second Task Force Report (Wild et al., 2009).  The universal English, Spanish and French versions were previously translated (Eremenco et al., 2012).  For the remaining languages, two forward translations by native translators, reconciliation of the forwards, one back-translation by an English-speaker fluent in the target language, and final reconciliation by a native speaking language coordinator were conducted for both measures.  Harmonization was performed to ensure conceptual equivalence across languages.  Interviews were conducted with five native-speaking COPD patients for each language/country combination. Interview data were analyzed to assess linguistic and cultural validity in each language and confirm conceptual equivalence. RESULTS: Mean age of the sample (N=80) was 60 years (range 41-83) and 54% were male. The translations were well understood and considered relevant, with patients raising only minor issues during interviews.  Changes were made to the universal French (chest congestion), Hungarian (wheezing, chest congestion), Italian (chest congestion, moderately), and Lithuanian (instructions, wheezing, shortness of breath, experienced) following the patient interviews. CONCLUSIONS: All translated versions of the NiSCI and EMSCI in this study were found to be conceptually equivalent and acceptable for use in the 14 countries evaluated.